562 MATNARD M. METCALF, 



in the two periods of normal structure and of degeneration. These 

 may throw some light on the meaning of the seasonal degeneration. 

 I will also include a description of the nature of the paranuclear 

 bodies in the ova of Salpa and of the rat, giving reasons for believing 

 that in both cases these bodies are ingested follicle cells or nuclei of 

 such ceUs. 



PizoN in a short paper in the Comptes Rendus Acad. Sc. Paris, 

 last year, described a remarkable series of changes through which 

 colonies of Botrylloides rubrum normally pass. The individuals of 

 a whole colony slough off the whole upper part of the body including 

 the pharynx, ganglion, neural gland, endostyle etc. until the spaces of 

 the test become filled with a degenerate mass of cells which are kept 

 in motion by the pulsation of all the hearts of the colony, which 

 remain alive and continue to beat. The individuals of the colony 

 regenerate the lost parts, until they become again of normal form. 

 After about a week the whole process will be repeated, and so on 

 for six or eight cycles of degeneration and regeneration. 



I have found many of my colonies of Leptoclinum alhidum in an 

 imperfect condition, with the upper parts of the bodies of the zoöids 

 absent. The material was carefully preserved, so this cannot be due 

 to improper manipulation, I believe the degeneration is a normal 

 process in the life history and that it is similar to the process de- 

 scribed by PizoN for Botrylloides. 



Some help in interpretating this strange habit may be gained 

 from a knowledge of the peculiar condition of the ovary in the 

 degenerate colonies of Leptoclinum. In the fully formed individuals in 

 a perfect colony of Leptoclinum the ovaries contain a very few very 

 large yolk-filled ova of the usual sort, having the characteristic double 

 follicle of the Tunicate ovum (Plate 38, Fig. 63). The testes are of 

 moderate size, showing spermatozoa in all stages of development. In 

 those colonies whose zoöids have lost the upper parts of their bodies 

 we find the testes about twice the usual size, with a larger proportion 

 of ripe sperm, and the ovaries, also, are much larger than in the 

 perfect zoöids of other colonies. These large ovaries contain a very 

 large number of small yolkless ova which have no follicular envelope 

 of any sort (Fig. 64). The ovary is in the form of a bag bent around 

 the intestinal mass, the lumen of the bag being, in section, a cres- 

 centic slit. The cells of that wall of the ovary which lies next to the 

 intestine are small. Some of those in the outer wall of the ovary 

 are small also, but many of them are much enlarged, as shown in 



