348 EDMUND B. WILSON 



preparations of other investigators, to whom I am under great 

 obligations. To Professor McClung I owe the loan of a beautiful 

 series of orthopteran preparations, especially of Phrynotettix, 

 Mermiria, Chortophaga and Achurum, which display on a larger 

 scale some of the same phenomena seen in the pre-synaptic stages 

 of the Hemiptera, and leave no doubt of the close parallel between 

 the two groups in this regard. Even more, however, I am in- 

 debted to Dr. and Madame Schreiner, and to Professor Janssens, 

 for some of their admirable original preparations of Tomopteris 

 and Batracoseps, which. have enabled me to make a prolonged 

 study of the phenomena of synapsis in these classical objects. 

 In particular, two magnificent slides of Batracoseps by Janssens 

 demonstrate both the complete seriation of the stages and the 

 finest details of the nuclear structures with incomparable clear- 

 ness. Though I have also made many preparations of this form, 

 as well as of Plethodon and other Amphibia, I must admit my 

 failure to equal in all respects the standard set by the slides of 

 Janssens. A close comparison of these various preparations has 

 more than ever impressed me with the futility of attempting the 

 study of these problems with material that is unfavorable for the 

 purpose, or with prepar'ations that in any respect fall short of the 

 highest standard of technical excellence. Nothing is more cer- 

 tain than that different objects differ enormously in the clearness 

 with which the relations are displayed, and in their reaction to 

 fixing and staining reagents. Had this been more generally recog- 

 nized, many erroneous conclusions and some ill-considered criti- 

 cism might have been avoided. . 



Through the study of Batracoseps and Tomopteris I have finally 

 been convinced for the first time, I must confess, as far as the 

 autosomes are concerned (1) that synapsis, or the conjugation 

 of chromosomes two by two 2 is a fact, and (2) that in these ani- 



2 A number of writers have suggested that the term synapsis, as here employed, 

 should be abandoned in favor of some less ambiguous word (such as Haecker's 

 term 'syndesis') because it has so frequently been applied to the contraction-fig- 

 ure ('synizesis' of McClung). I am, however, in favor of the retention of the 

 word, for the ambiguity has arisen simply through a misunderstanding of Moore's 

 meaning. He applied the term 'sj^naptic phase,' or 'synapsis,' to the series of 

 changes following the last diploid division (during the 'rest of transformation') 



