NUTRITION 291 



comparative simplicity of structure of the " lower " organisms, we are more likely 

 to be able to discover what is the essential nature of these processes, if we devote 

 our attention to the apparently simpler creatures. 



Without denying the great value of the comparative method in eliminating 

 merely incidental phenomena, it must be pointed out that this very simplicity is, 

 in the majority of cases, a disadvantage. The same organ, or even cell, fulfils a 

 variety of purposes, which in the higher organisms are relegated to distinct groups 

 of cells. Moreover, the size of the organism is of much importance, as will have 

 been sufficiently obvious in the present chapter. The science of nutrition would 

 be almost impossible without the larger, warm-blooded animals. The advantage 

 of the increased rate of reactions, owing to the higher temperature, is not to be 

 undervalued. 



The physiology of unicellular organisms, although of considerable importance 

 in special aspects, is not to be regarded as a "general physiology." Indeed, if 

 the choice had to be made between the investigation of simple or complex 

 organisms alone, there is no doubt that a much more general and fundamental 

 body of doctrine would be obtained from the latter. 



The following remarks of Claude Bernard (1866, p. 100) may be read with interest : "II ne 

 faudrait pas croire, en effet, que 1'animal inferieur est plus simple ou que ses fonctions sont 

 moins compliquees ou moins nombreuses ; et qu'on pourrait les prendre pour ainsi dire a leur 

 naissance, pour suivre ensuite leur developpement dans les animaux superieurs, qui auraient 

 ainsi des proprietes nouvelles se surajoutant aux premieres. L'animal inferieur possede toutes 

 les proprietes essentielles qu'on retrouve aux degres les plus eleves de 1'echelle des etres ; mais 

 il les possede a 1'etat confus, et pour ainsi dire repandues dans toutes les parties du corps. 

 Ainsi 1'infusoire, qui s'agite et se dirige dans le liquide ou il a pris naissance, possede evidm- 

 ment la propriete de se mouvoir ; il doit etre doue de sensibility pour determiner ses mouve- 

 ments ; enfin, il peut se reproduire, puisque 1'espeee ne perit pas. Voila done la vie a son degre 

 le plus infime, avec toutes les fonctions qu'elle manifeste chez les animaux eleves. Mais quand 

 on cherche les organes de chacune de ces fonctions, on ne peut plus rien distinguer, et c'est & 

 ce point de vue seulement qu'on doit parler de la pretendue simplicite des animaux inferieurs." 



REPRODUCTION 



In the most primitive state it frequently happens that the whole cell contents 

 of an organism divide into a number of smaller parts, each of which gives rise 

 to a new organism. In such a process the new organisms are endowed only 

 with the qualities of the one cell. Since the powers of adaptation of any two 

 organisms or cells are not, as a rule, identical, it is clear that if the new organisms 

 could "inherit" the characteristics of more than one it would be to its advantage. 

 Accordingly, we find, very early in the course of evolution, arrangements by 

 which two cells join their forces by fusion or conjugation. At first, the two cells 

 are similar, as in Spirogyra, but almost at once we find a differentiation by which 

 a large cell, called the female cell or gamete, is incapable of further development 

 without fusion with another smaller, usually motile, cell, the male gamete. The 

 great variety of arrangements by which this " fertilisation " is effected or facilitated 

 are beyond the scope of this book and will be found in the textbooks of botany 

 and zoology. The main point to be kept in mind is the incapability of either 

 the male or female cell alone to grow to a new organism. Since it is the female 

 cell which remains more or less stationary and is, as it were, sought out by the 

 male cell, while the new organism grows from the fertilised female cell, the obvious 

 effect of the male cell is to set into activity the dormant powers of segmentation 

 and growth of the female cell. It is easy thus to lose sight of tlie fact that the 

 male cell also brings with it the capacities of the organism from which it has 

 arisen. 



The mysterious power of the male has from the earliest times excited wonder 

 and has, not unnaturally, become the object of religious worship. It is indeed 

 greatly to be regretted that the sexual process should have become the subject 

 of unseemly jesting. Of course, incidents of real humour may arise in any 

 connection, "without detriment to its essential solemnity, as witness the great art 

 of Shakespeare. But I feel compelled to state my belief that much mischief 

 is done by the habit of looking upon anything related to sex as, in itself, a 



