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Iprot i£. (3. Balbiani'e IReeearcbee on tbe 

 flDerotomv of CUtatcb 3nfu6onan6,* 



By Filandro Vicentini, M.D. (Chieti, Italy). 



PROF. Balbiani defines Merotomy as being the operation 

 which consists in the separating or cutting from a living 

 organism, a more or less considerable portion, for the 

 purpose of observing the anatomical and physiological modifica- 

 tions of the isolated part. 



In a previous paper f on the subject of artificial division, Prof. 

 Balbiani traced the work of earlier writers, and gave a detailed 

 account of the structure of Cyrtostomum leucas, and his study of 

 the effects of merotomy on this species. He found that the 

 merozoite, or fragment of the individual, which contained the 

 nucleus, or a part of the nucleus, was alone capable of regenera- 

 tion — namely, of constituting an individual similar, though smaller, 

 to the original. Studies of Trachelis ovum and Prorodo7i nivens 

 yielded essentially the same results. 



In the present work. Prof. Balbiani describes some interesting 

 experiments which he has made upon Stentor cceruleus. After 

 comparing them with those of Gruber on the same species, he 

 gives a detailed account of the various phases presented, from 

 which we abstract the following : — 



A.— Merotomy of S. cceruleus by artificial division.— In 



transverse sections intersecting the nuclear chain the anterior 

 merozoite has to reproduce the rudder and the posterior sucker, 

 but these are generated in less than twelve hours. The pos- 

 terior merozoite has to reproduce a mouth, a peristome, and a 

 new contractile vesicle. Should the Stefitor be divided into three 

 fragments, the middle one, containing a portion of the nuclear 

 chain, regenerates in twenty-four hours the missing extremities, and 

 the other portions behave as above. Should either of the pieces 

 not contain a portion of the nucleus, it is not converted into a 

 complete individual ; but the protoplasm degenerates, becoming 

 spongy, and dies in about twenty-four to forty-eight hours. 



* Annales de Micro. , I v. (1892), pp. 396 — 407, 449 — 489 (3 plates). 

 \ Recueil Zool. Suisse, v. (1888), pp. i — 72 (2 plates). 



