1897. CHROMOSOME-REDUCTION AND WEI SM ANN. 409 



and consequently the theoretical value of the remaining observations 

 of Riickert and Hacker has in this respect vanished altogether. 



Naturally I have no wish to question the accuracy of 

 Riickert and Hacker's work on the Arthropoda. If the process 

 they describe really occurs in these animals, it is certain that it 

 simply exemplifies a diversity in the phenomena of maturation, 

 which at once abolishes all the theoretical importance of reduction, 

 in the sense in which these authors originally employed it. In 

 fact it cannot be too clearly stated at the present time, that 

 Hacker's, no less than Weismann's, attempt to support the theory 

 of reduction on a basis of observed facts, has altogether broken 

 down. 



The state of our knowledge on this subject being then in the 

 unedifying condition I have just described, it is not a little unfortunate 

 that, in his work " The cell in development and inheritance " 

 Professor Wilson should have given the by no means impartial 

 description of these processes that is to be found in the chapters 

 dealing with reduction.' As this book is popularly written, it is 

 likely to be widely read, and the incorporation of erroneous observa- 

 tions in support of the theoretical conclusions it contains can only 

 perpetuate that obscuration of the facts which the reiterated 

 assertion of the universal occurrence of the new reduction has already 

 produced. 



J. E. S. Moore. 

 Royal College of Science, 

 London, S.W. 



1 On page 189 Professor Wilson also attributes to me the assertion that the ring 

 chromosomes do not arise by a longitudinal splitting of a primary chromatin rod. 



Had he taken the trouble to read page 289 of my paper " On the 



Spermatogenesis of Elasmobranchs [Quart. Jour u. Micro. Set. vol. xxxviii., Part II, 

 pp. 275-313, 1895) before misquoting it, he would have found the following passage 

 describing the origin of the heterotype rings : " The polarised thread- work is disposed 

 throughout the nucleus in long parallel loops, the free ends of which, if they exist, 

 are difficult to discern. After a time the threads begin to show longitudinal 

 splittings, the double ropes thus formed dividing into equal segments, eventually 

 giving rise to twelve thick loops, which form the twelve ring chromosomes, typical 

 of the division of the second spermatogenetic period." 



[For Literature, see over. 



G 



