548 CLARENCE E. McCLUNG 



The work of Delia Valle is open to criticism from two sides. 

 It may in the first place, well be questioned whether the knowl- 

 edge of colloid chemistry, and of fluid crystals in particular, is 

 sufficiently established to justify the extension of its principles 

 into the operation of cellular phenomena. Certainly one is in- 

 clined to doubt the basis on which such application is made 

 when the compUcated phenomena of chromosome division are 

 declared to be 'absolutely identical' with the cleavage of fluid 

 crystals, or when the involved changes of the chromatin in the 

 telophase are described as 'identical' with the solution phe- 

 nomena of a gelatin cylinder in warm water. It is of course 

 hot to be doubted that in the activities of the chromosomes, 

 and all parts of the cell indeed, chemical and physical laws are 

 operative. Such a belief is however far removed from the one 

 which conceives some particular manifestation of chemical or 

 physical energy as 'identical' with the behavior of the chromo- 

 somes in mitosis. Much might properly be said with regard to 

 this phase of Delia Valle's work, but I desire rather to consider 

 the nature of what he advances as direct evidence against the 

 theory of chromosome individuahty. Since this involves a 

 thoroughgoing denial of all the facts and theories relating to the 

 subject, such a discussion wall touch upon most of the objections 

 that have been raised by other critics and will avoid the neces- 

 sity for repeating arguments involving only minor differences of 

 material or opinion. A summary of his position with regard 

 to matters relating to chromosome individuality follows: 



He asserts that the number of chromosomes in a cell is due to 

 the constancy in the amount of the chromatin and the median 

 size of the .single chromatin aggregates. This number suffers 

 variation according to the law of fluctuating variations and is 



acceptance to attack the motives of those who hold other opinions. A method 

 does not commend itself as an instrument of value merely because it is termed 

 an 'objective analysis' when it is obviously the application of a series of anal- 

 ogies. Neither does an observed fact cease to be such on being termed a 'hy- 

 pothesis' or even a 'subhypothesis.' It is in fact not infrequently true that 

 much of good in the work of certain biologists issues under a severe handicap 

 because of the inherent evidence of poor judgment in their estimation of values 

 in the work of others. 



