432 
George Arnold 
difficult to understand wby tliis interpretation of the formation of 
the gemini should be rejected. except for an extreme desire for 
cytological uuity. 
On the otlier band, tbe above interpretation of tbe manner of 
the formation of the heterotype gemini bas been supported by Mot- 
tier, Schaffner, Montgomery, Meves, Goldschmidt, Popoff and 
Farmer-Moore, to mention no otliers. Of tbe work of the latter 
autbors, Gregoire '07) complains tbat thev have entirely overlooked 
the stages vrhieh he ealls leptoteue and zygotene. "D’autre part, 
Farmer-Moore, ainsi que nous verrons ont completement neglige 
dans leurs recherehes l’etude des noyaux leptotenes et zygotenes; ils 
passeut directement du stade de reseau au stade de pachynema ou 
spireme epais." 
Xow in botli tbe ovi-and spermatogenesis of PL lactea tbese two 
stages can be rnade out witb great clearness, but as xvill be subse- 
quently sbown tbey do not support Gregoire' s interpretation of lon- 
gitudinal approximation. 
Before proceeding to describe in detail tbe propbasic cbanges 
which form the subject of tliis paper, it is necessary to consider tbe 
pbenomenon of synapsis, and tbe view entertained by some autbors 
tbat it is an artifact, resulting from imperfect fixation. Tbis is the 
opinion of amongst otliers Meves, Gregoire, Jannsens, Molle, and 
in spite of tbe fact tbat tbe synapsis bas been seen in living cells 
by Miss Sargext '97) and Berghs ( : 04). Jaxxsexs ('05) declares 
tbat at tbis particular stage, the nucleus possesses a marked sensi- 
bility to tixatives (..uue sensibilite toute speciale aux reactifs”) and 
tbat it probably contains a substance ..susceptible de coagulation 
facile avec eontraction eoneomitante”. For tbis bowever be brings 
forward no proof, and it can but be regarded as a gratuitous as- 
sumption. True, be savs tbat in badly fixed testes of Batrochoseps , 
synaptene nuclei are numerous. But if tbe presence of numerous 
cells in tbe synaptic stage is to be regarded as tbe criterion of bad 
fixation, tbat is merely begging the question. 
Meves opinion is qnite clear. Reviewing tbe synapsis in bis 
paper on tbe spermatogenesis of tbe Honey-bee ( : 07) be says: ..Was 
nun zunächst die Zusammenballung anbetrifft, so bin ich durchaus 
der Meinung, daR sie einzig und allein durch die Wirkung der 
angewandten Reageiltien hervorgebracbt wird. . . . Jedoch muß die 
Tendenz des Cbromatingeriistes, zu einer bestimmten Periode sieb 
zusammeuzuzieben, zugegeben werden: denn auf Stadien, die vor oder 
