560 Organic Physics. fjuly, 



justice look upon the cells as individuals, and as, in their methods 

 of development, concerned only for their own private interests. 

 In the Protozoa the new cells are all set free because there is no 

 advantage to be gained by their remaining coherent. In the 

 Metazoa there is an advantage to be gained by coherence. They 

 are adapted to a special nutriment, which is brought to them, and 

 which they would fail to obtain unless united into a specialized 

 organism. But the nutrient fluid from which they derive food, 

 offers also a sphere of advantageous free existence. The cells 

 are equally well situated when free as when coherent, and there- 

 fore the newly-formed cells are as likely to become free as to re- 

 main coherent. Possibly they have a somewhat better chance for 

 life in the free state, as they are surrounded by a nutrient fluid 

 exactly suited to their needs. Hence the free buds rapidly develop 

 into actively vital cells, yielding what are known as the lymph 

 corpuscles. 



But these corpuscles are contained in a moving fluid. They 

 are quickly borne away from their point of origin and thrown 

 into the blood. Here the conditions for their free life are less 

 favorable. They may fail to obtain the specially elaborated nutri- 

 ment to which they are adapted, and thus may lose their vitality 

 and possibly become modified into the red blood corpuscles. 



The struggle for existence may be active between the leuco- 

 cytes in the blood. Beale and Max Schultze describe minute 

 globules in the blood which they suppose to be fragments (or 

 gemmules) budded off from the white corpuscles. These may 

 serve as nutriment to other corpuscles. If so the corpuscles must 

 gradually acquire molecular conditions arising from varied re- 

 gions of the body, and thus become more generalized in constitu- 

 tion and better adapted to the nutrient conditions of the blood. 

 Possibly a considerable degree of generalization may be at- 

 tained in this manner. 



This process of cellular budding and the formation o( free 

 cells, is continuous throughout life. It has its phases of variation 

 in the daily life of organisms. The leucocytes appear more 

 abundantly after meals, and decrease in number during abstinence. 

 But the nutrient and developing activity of the cells must display 

 this same variation. Possibly the process of free budding may 

 be more active in mature life than in youth. The rapidity oi 

 growth in youth indicates a strong tendency to coherence of ce s, 



