58 KANSAS UNIVERSITY QUARTERLY. 



No. 31. C. imniu7iis. F. II. About three inches long. Slightly 

 soft from exuviation. April 20, 1900 



Two lobes sectioned. Condition same as No. 26. 



No. 32. C. immunis. F. II. About two and one-half inches long. 

 Very soft from exuviation. April 21. 1901. 



One lobe sectioned. Condition seems to be about the same as No. 36. Vas 

 deferens well filled with spermatozoa. 



No. 38. C. immunis. F. I. About two and one-half inches long. 

 Did not seem to be nearly ready to exuviate. April 21. 1901. 



One lobe sectioned. Condition much the same as in No. 31. Vae deferens 

 well filled with spermatozoa. 



No. 34. See body of paper, pages 50 and 51. 

 No. 35. See body of paper, pages 50 and 51. 



No. 36. C. immunis. F. II. About three inches long. Kept in 

 laboratory in second-form condition eight days. May 5, 1901. 



Two anterior lobes sectioned. Condition much the same as in No. 21. Sper- 

 matocytes perhaps somewhat more numerous, and spermatogonial region more 

 extensive. 



No. 37. C. imnumis. F. II. About three inches long. Had been 

 kept in the laboratory. Had been in second-form condition at least 

 ten days. May — , 1901. 



One lobe sectioned. In this specimen nearly all the spermatogonia have gone 

 over into early spermatocytes. The region of spermatocytes is proportionately 

 considerably larger than the spermatogonial region in any of the above-mentioned 

 material. The vas deferens is well filled with spermatozoa. 



From an examination of Nos. 1 to 18 it will be seen that no constant 

 differences can be demonstrated between the testes of tirst- and second- 

 form males collected in the late summer. The material examined in- 

 cludes specimens yet comparatively soft from exuviation as well as 

 those which have apparently been in first- or second-form for a con- 

 siderable length of time. An examination of Nos. 21 to 37 shows that 

 in the spring ecdysis, as well, no definite difference which might de- 

 termine the time of the change of form is to be observed. 



The list of material described above tends to show that the main 

 part of the regeneration of the male sexual elements takes place be- 

 tween the spring exuviation, in which the animal assumes the second- 

 form, and late in August, and that during the latter portion of this 

 period the animal may be in either of the forms. The later stages 

 of regeneration take place, so far as I have been able to observe, in 

 exactly the same manner, whether the animal is first- or second-form. 



While advancing this theory rather tentatively, it seems to me that 

 from the evidence at hand we must conclude that the second-form 

 represents the period in which the greater part of the regeneration of 



