REVERSAL OF FUNCTION IX OLIGARCES. 14! 



previou-ly stated, 7 days later, the larva was found to contain 4 

 young embryos and 10 eggs. In the same culture another pupa- 

 lurva was observed with two large embryos, while other pupa- 

 larva- were observed containing varying numbers of embryos, 

 though in no case more than four. On January 8, young larva' 



ped frm -e\eral mothers, which had all the morphological 

 oh. 11 sties "f pupa-larvae. These young, 33 in number, 



were typical p.edogenetic larva?, and later produced young 

 pa-do-i -in -tii .illy in their turn. Of the total of 40 pupa-lai \ ,r 

 (\vhirh were tran-terred from culture MP 142), 27 metann irpho-n 1 

 into pupa-, .UK! tlu-se in turn into adult flies, while 13. >ho\\ii 

 ersal of function, did not metamorphose but i rise to 



;n .1 typically paedogenetic fashion. 



Sim.- I h.id already observed that pupa-larva- could be pro- 

 duced .it \vill in the laboratory from a \ genetic strain 1>\ 

 i j'.udin^. ji -ct-med probable that the appart-ni n.-\tr-.il <-l 

 function was < ailed forth by a reversal of the external conditions 

 -niTouinliiiv. 'he pupa-larvae. Thus the tran>!Vn-ni i of a pupa- 

 lar\.i to .i iiv-h culture immediately renioxed them from tin 

 inthiciKc oi (iM\vding, thus reversing the external conditions to 

 which they h.nl been subjected. 



The fat t that some of the pupa-larvae seemed to respond to the 

 in 1 1 men i , \\ hile others did not, suggested the |><>^il>ilit\ that the 



"t tin larva*, when transferred, and by consequence tin si 

 oi de\elopment of the gonads and eggs, determined whether or 

 not a re\ci-.tl of function would occur. 



1 1 m.i\ lu-aid that the material upon which these observations 

 \\ete in. ule is a female producing strain (Hani-, [924). The 

 |iie>tioii then probably resolves itself into \\hether or not the 



- ha\ e leached a stage at which par the in '-cue tic reproduction 

 is no longer p< '--ible.) 



In order to ,i-. ertain if the apparent reversal of function \\eie 

 due i to the release from crowding, and from the ronM-i|iirnt 

 presence -of an unusually large amount of the by-products of 

 metabolism ; oi if it \\ere dependent upon (2) the age of the pupa- 

 lar\a- \\hen released from crowding, another series of experiments 

 \\-as carried mi. u-m^ the same stock in the second subsequent 

 generation. In thi> generation pupa-larvae arose, esult of 



crowding during embryonic developement, in culture M JJJ, 



