VITALITY 481 



diiced when the samples are collected and transferred to small 

 holders in the laboratory. With such an individual con^'incing 

 proof is apparently impossible and we can only ignore the implica- 

 tion that conjugation is a phenomenon which did not occur under 

 "normal" conditions in Nature Init manifested itself only when 

 man began to collect material. I have no sympathy with such a 

 point of view; I regard conjugation as an entirely "normal" process 

 in ciliates as gamete formation and fertilization are "normal" 

 processes in Sporozoa and Sarcodina. When the conditions of the 

 en^•ironment are such that this phenomenon does not occur, then 

 we may justly look for the unusual at least. The limits of adapta- 

 tion of protoplasm are unknown to us; it is quite conceivable that 

 conditions may be so arranged that for long periods the normal 

 sequence of phenomena in a life cycle are in abeyance and the 

 impression is gained that protoplasm under such conditions has 

 the possibility of indefinitely continued existence. But can this be 

 considered a normal environment? Here the conditions which 

 lead to conjugation are not offered and such conditions, if any, 

 might reasonably be regarded as abnormal; if conjugation is needed 

 the need is met by the artificial conditions and the organism is more 

 or less adapted to them. Xo one can maintain consistently that 

 Carrel's long-continued tissue cultures are normal, yet here we have 

 artificial conditions under which these vertebrate tissue cells 

 continue, apparently indefinitely, to live and divide. Death of 

 cells occurs when the transfers are not made at appropriate inter- 

 vals, but they have become adapted to the artificial conditions of 

 cultivation and continue to Vixe anfl di^•ide so long as these condi- 

 tions are maintained. 



The question of "normal" or "abnormal" environment after all, 

 appears to me to be of an academic nature, and I cannot agree with 

 Woodruff and his followers in their belief that natural death is 

 not inherent in ciliates under natural, or as he calls it, "normal" 

 conditions. Xor can I accept his further conclusion that the life 

 cycle of a ciliate is a "myth." It is quite evident that the cycle 

 may be greatly varied by reason of external conditions and it is 

 plainly obvious that it has no definite or fixed limits such as postu- 

 lated by ]\Iaupas. If fertilization is an almost universal phenomenon 

 we should be able to determine the conditions which bring it about 

 both Avithin the protoplasm and in the environment. If fertiliza- 

 tion satisfies a protoplasmic need we should be able to find out what 

 that need is. When that explanation is forthcoming we shall 

 probably be able to understand why the animal flagellates continue 

 to live so successfully without it. 



In regard to the life cycle of Protozoa we are apparently all 

 agreed on some cases. Since the classical work of Schaudinn 

 (1900) on Eimeria {Coccirliuni) schiibergl no one doubts the general 

 31 



