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NEW VIEW OF THE MECHANISM OF RESPIRATION 299<br />
is, however, not necessary to elaborate the subject further. It will suffice if I reiterate my statements to the efiect<br />
that the rhythms and reflexes referred to are the product of fundamental structures, which have their roots deep<br />
in the constitution of things, and that they are necessary, in one shape or other, to the very existence of plants and<br />
animals in their simplest and most complex forms. The rhythms and reflexes to which allusion is now made are not<br />
the ofEspring of chance, of irritability, stimulation, or environment. They are movements per se, and the more<br />
closely they are scanned, the more mysterious and inexplicable do they become unless a First Cause is predicated.<br />
There is no getting behind or understanding them imless a First Cause be taken for granted. With a Creator, the<br />
whole scheme of original endowment and movement lies open to the gaze of even the most casual observer.<br />
TRANSITION LINKS AS BETWEEN THE PLANT AND ANIMAL<br />
The breathing of animals has been fully described and illustrated under " The Eespiratory Organs in Animals,<br />
and especially in Man " (page 274, Section 55, Plates Ixxvii. and Ixxviii., Figs. 45 to 57 inclusive). The muscular<br />
arrangements and movements in animals are described and delineated very fully in Plates Ixxxiii., Ixxxiv., and Ixxxv.,<br />
Figs. 67 to 75 inclusive. The part played by the muscles in the production of alimentation, respiration, circulation,<br />
urination, reproduction, and locomotion are dealt with in detail in different parts of the work.<br />
§ 57. The Mycetozoa.<br />
These remarkable organisms form a numerous family, and are pretty well universal as regards distribution,<br />
being found in Europe, India, the Cape of Good Hope, Australia, North and^South America, &c. As many as one<br />
hundred and seventy-five species are preserved in the Botanical Collection of the British Museum, and, curious to<br />
relate, as establishing the cosmopohtan nature of the family, quite a large number of species exhibit precisely the<br />
same characters on different parts of the earth's surface.<br />
Great interest attaches to the Mycetozoa physiologically because of their mode of reproduction, their independent<br />
amoebic and plasmodium movements, their mode of feeding, their tenacity of life, and their power of subsisting in<br />
essentially two different conditions, namely, in a desiccated or dried-up, inactive, or hibernating condition (sclerotium),<br />
and in a moist, swarming, streaming, active condition. These several points are illustrated at Figs. 58 and 59.<br />
The dual life of the Mycetozoa, namely, its inactive, resting condition (Fig. 59, A) ; its power of swarming<br />
(Fig. 58, A, B, C) ; and its aggressive nature in the active or streaming state (Fig. 59, B, C, D, B), are especially outstanding<br />
features, and deserve the careful attention of biologists, as they reveal a potentiality, structurally and<br />
functionally, which goes far to prove that protoplasm and life are endowed with what are virtually universal<br />
powers. The life history of the Mycetozoa certainly shows that reproduction, ingestion, digestion, absorption,<br />
assimilation, and movements more or less co-ordinated and definite can be produced in the simplest manner, and<br />
with httle or no differentiation. It also shows that these processes, in the higher animals up to man himself, are<br />
not necessarily dependent on the existence of a nervous system ; as a rule, that system controlling but not<br />
causing them.<br />
It is important to direct the attention of the reader to this fact, as the trend of late years is to accredit the<br />
nervous system, in the higher animals, with every change, physical and mental, which occurs in the animal economy.<br />
It is quite obvious that the movements,;rhythmic and otherwise, occurring in plants and a very large number<br />
of the lower organisms, are in no way dependent on nerves ; these being non-existent, or, at all events, not assum-<br />
ing a defijiite or palpable form. It is reasonable to assume that the movements connected with ahmentation,<br />
respiration, circulation, secretion, excretion, &c., all of which are necessary to the life and well-being of the m-<br />
dividual, are pre-arranged, original, inherent, and independent movements. An example will bring out my meaning.<br />
The heart of the chick beats regularly while yet a mass of nucleated cells, and before it is provided with muscles<br />
and nerves, and even before it contains blood.<br />
To borrow an illustration from the Mycetozoa themselves. The plasmodium of Badhamia utricularis streams<br />
out in search of food in fan-shaped, skirmishing order, and covers an area of forty or more square inches ;<br />
its Uttle<br />
advancing fans, two or three hundred in number, springing from a network of branches (Fig. 59, B, C, D, E).<br />
When food, say a portion of Stereum Urswtum, is placed at the root of the network, the little advancing fans<br />
and the network itself are simultaneously withdrawn, and the plasmodium, voluntarily as it were, concentrates<br />
on the food, which it steadily and slowly devours. The skirmishing order may be maintained for two whole days,<br />
while the concentration occurs in five hours.<br />
Here we have what is virtually a voluntary effort put forth by an organism which, according to some, is a