62 SUMMARY OF CURRENT RESEARCHES RELATING TO 



thoroughness of the information which ho has given, and at the 

 soundness of the conclusions at which he arrived." 



Dr. Hoek observed the complemcntal male in 19 out of the 41 

 new species described in the first part of the report, but the unique 

 specimens were not, and could not without spoiling them, be 

 thoroughly examined. The structure of these males varies ; some 

 do not show a division of the body into a capitulum and a peduncle ; 

 a second gi'oup, while not showing either, are furnished with 

 rudimentary valves ; and a third not only have these latter but also 

 show a distinct capitulum and peduncle. Another chapter treats of 

 the anatomy of the complemcntal male in Scalfellum ornatum, one of 

 the largest known. 



The subjects of the Cjfpm-larvse, of the segmental organs in the 

 Cirripedia, of the cement apparatus, of Darwin's " true ovaria " 

 (believed to be a pancreatic gland), the eye in Lepas, and the 

 gynoecial organs, are also treated of. 



Vermes. 



Nervous System of Archiannelides.* — J. Fraipont has inves- 

 tigated the central and peripheral nervous system of Profodrilus, 

 Pohjfjordius, and Saccocirrus papillocercus. After an historical review 

 of what has been already done, he gives an account of the methods 

 employed by him, the first of which was the study of living spe- 

 cimens ; for microscopic examination specimens are best killed by 

 the gradual addition of alcohol to the sea water in which they are 

 living ; the worms were then hardened by strong alcohol, osmic or 

 picric acids, or hot or cold corrosive sublimate. The great point to be 

 aimed at is getting the animals as extended as possible. Borax- 

 carmine, picrocarminate of ammonia in 99 parts of alcohol, hsBma- 

 toxylin, and anilin dyes were the favourite staining reagents. 

 Sections were made by Jung's microtome, and the fixing method of 

 Giesbrecht was adopted. 



The relations of the nervous system of Protodrilus to the 

 ectoderm arc very characteristic, and present as a permanent 

 arrangement that which is seen only in the larval stages of higher 

 annelids ; it remains intimately connected with the epidermis ; there 

 is no differentiated wall by which the nervous cells are separated from 

 the rest. But, further, its structure as well as its position is 

 remarkable for its primitive character ; in a single section one may 

 see transitional stages between the ganglionic and the ordinary 

 epidermic cells. We may say that the whole frontal lobe is cerebral ; 

 it is a thickening of the ectoderm which only contains ectodermal 

 cells ; such as are superficial in position retain the characters of 

 investing cells ; those that are deeper are nervous in nature. It is 

 scarcely possible to distinguish a grouping of ganglionic cells, but 

 two posterior masses must be regarded as representing two ganglia 

 with the special function of innervating the ciliated pits. In the 

 ventral cord the ganglionic cells are distributed uniformly over the 



* Arch, de Biol., v. (1884) pp. 243-304 (5 pis.). 



