NEW VIEW OF THE MECHANISM OF RESPIRATION 299 



is, however, not necessary to elaborate the subject further. It will suffice if I reiterate my statements to the efiect 

 that the rhythms and reflexes referred to are the product of fundamental structures, which have their roots deep 

 in the constitution of things, and that they are necessary, in one shape or other, to the very existence of plants and 

 animals in their simplest and most complex forms. The rhythms and reflexes to which allusion is now made are not 

 the ofEspring of chance, of irritability, stimulation, or environment. They are movements per se, and the more 

 closely they are scanned, the more mysterious and inexplicable do they become unless a First Cause is predicated. 

 There is no getting behind or understanding them imless a First Cause be taken for granted. With a Creator, the 

 whole scheme of original endowment and movement lies open to the gaze of even the most casual observer. 



TRANSITION LINKS AS BETWEEN THE PLANT AND ANIMAL 



The breathing of animals has been fully described and illustrated under " The Eespiratory Organs in Animals, 

 and especially in Man " (page 274, Section 55, Plates Ixxvii. and Ixxviii., Figs. 45 to 57 inclusive). The muscular 

 arrangements and movements in animals are described and delineated very fully in Plates Ixxxiii., Ixxxiv., and Ixxxv., 

 Figs. 67 to 75 inclusive. The part played by the muscles in the production of alimentation, respiration, circulation, 

 urination, reproduction, and locomotion are dealt with in detail in different parts of the work. 



§ 57. The Mycetozoa. 



These remarkable organisms form a numerous family, and are pretty well universal as regards distribution, 

 being found in Europe, India, the Cape of Good Hope, Australia, North and^South America, &c. As many as one 

 hundred and seventy-five species are preserved in the Botanical Collection of the British Museum, and, curious to 

 relate, as establishing the cosmopohtan nature of the family, quite a large number of species exhibit precisely the 

 same characters on different parts of the earth's surface. 



Great interest attaches to the Mycetozoa physiologically because of their mode of reproduction, their independent 

 amoebic and plasmodium movements, their mode of feeding, their tenacity of life, and their power of subsisting in 

 essentially two different conditions, namely, in a desiccated or dried-up, inactive, or hibernating condition (sclerotium), 

 and in a moist, swarming, streaming, active condition. These several points are illustrated at Figs. 58 and 59. 



The dual life of the Mycetozoa, namely, its inactive, resting condition (Fig. 59, A) ; its power of swarming 

 (Fig. 58, A, B, C) ; and its aggressive nature in the active or streaming state (Fig. 59, B, C, D, B), are especially out- 

 standing features, and deserve the careful attention of biologists, as they reveal a potentiality, structurally and 

 functionally, which goes far to prove that protoplasm and life are endowed with what are virtually universal 

 powers. The life history of the Mycetozoa certainly shows that reproduction, ingestion, digestion, absorption, 

 assimilation, and movements more or less co-ordinated and definite can be produced in the simplest manner, and 

 with httle or no differentiation. It also shows that these processes, in the higher animals up to man himself, are 

 not necessarily dependent on the existence of a nervous system ; as a rule, that system controlling but not 

 causing them. 



It is important to direct the attention of the reader to this fact, as the trend of late years is to accredit the 

 nervous system, in the higher animals, with every change, physical and mental, which occurs in the animal economy. 



It is quite obvious that the movements,;rhythmic and otherwise, occurring in plants and a very large number 

 of the lower organisms, are in no way dependent on nerves ; these being non-existent, or, at all events, not assum- 

 ing a defijiite or palpable form. It is reasonable to assume that the movements connected with ahmentation, 

 respiration, circulation, secretion, excretion, &c., all of which are necessary to the life and well-being of the m- 

 dividual, are pre-arranged, original, inherent, and independent movements. An example will bring out my meaning. 

 The heart of the chick beats regularly while yet a mass of nucleated cells, and before it is provided with muscles 

 and nerves, and even before it contains blood. 



To borrow an illustration from the Mycetozoa themselves. The plasmodium of Badhamia utricularis streams 

 out in search of food in fan-shaped, skirmishing order, and covers an area of forty or more square inches ; its Uttle 

 advancing fans, two or three hundred in number, springing from a network of branches (Fig. 59, B, C, D, E). 



When food, say a portion of Stereum Urswtum, is placed at the root of the network, the little advancing fans 

 and the network itself are simultaneously withdrawn, and the plasmodium, voluntarily as it were, concentrates 

 on the food, which it steadily and slowly devours. The skirmishing order may be maintained for two whole days, 

 while the concentration occurs in five hours. 



Here we have what is virtually a voluntary effort put forth by an organism which, according to some, is a 



