181] LIFE HISTORY OP GORDIUS AND PARAGORDIUS—MA Y 61 



scientific value. His specimens were rendered unfit for histological inves- 

 tigation by the methods he employed in removing and killing the parasites. 

 As proof it is merely necessary to consider his figures and interpretations 

 of the hypoderm. I have obtained essentially the same results in specimens 

 that were removed in water and were not properly killed. In that case 

 the cells shrink and appear as small, deeply staining bodies with the inter- 

 cellular bridges forming radiations from these centres. The whole mass 

 appears as a network such as Villot (1874) has figured. 



Even Vejdovsky's work is not free from similar defects. The figures 

 of the degenerating nuclei are certainly nothing more than those of poorly 

 preserved nuclei in which parts of the nuclear structures had been macer- 

 ated out. Naturally different stages of such a process would be found. He 

 supplies part of the evidence for that himself in stating that the specimens 

 obtained from Camerano, which were preserved in alcohol and were other- 

 wise in very poor condition, gave him the best results in the study of these 

 stages in the nuclear changes. Vejdovsky was handicapped in many ways. 

 He was unable to cut sections less than 20 n thick and had at his disposal 

 no better stains than the carmins. 



In regard to the morphology of the adults all the papers except those 

 of Montgomery, Vejdovsky, Rauther and ^vabenik are of little scientific 

 value because the investigations were either too fragmentary or they were 

 carried out under conditions that could produce no accurate results. The 

 present investigations show that all conclusions based purely upon adult 

 structures are subject to verification. It is impossible to interpret properly 

 the adult structures of the Gordiacea without knowing something about 

 their development. 



Metamorphosis 



Altho the present work gives some information in regard to the meta- 

 morphosis of the two species studied, there are many questions that still 

 remain unanswered. There exists no previous literature on this subject. 

 Montgomery (1904) and after him Miihldorf assumed that the proboscis 

 of the larva is a precephalon and does not take part in the development. 

 The present investigations show that this is not the case, but that the brain 

 of the adult in both of the species examined develops from the posterior 

 part of the proboscis, and that even the cord of tissue connecting the stylets 

 with the partition between proboscis and body, representing possibly the 

 larval esophagus, develops in one of the species. 



The present investigations have also for the first time revealed the fact 

 that the larval cuticula is shed when the parasite attains its full develop- 

 ment and that the remnants of the larval proboscis which do not take part 

 in development are lost with the larval cuticula. 



