240 Ohservations on some points in [*jTumIi, MayTi«7o!'' 



matter to embryonic nervous tissue. It is well known that in the 

 jDrimary phases of the development of the cord, it is the cells of the 

 grey matter that are first formed, and then the fibres. 



4. The apparent improbability of the generation in an adult 

 animal of orgi unites occupying, in the series of histological elements, 

 so high a rank as that of ganglionic cells. 



This improbability disappears when we consider the favourable 

 conditions found united in the frogs operated on, and previously- 

 observed facts. The production is in fact entirely homoplastic, and 

 the protection afforded to the cord by the vertebral canal prevents 

 any external influence from checking the reparative process. Besides, 

 Yoit and Kollmann have already proved the neo-genesis of the 

 nervous cells, and Beale has seen in the ganglia of the adult frog a 

 continuous formation of the same cells. 



The want of success of previous experimenters is due to their 

 having neglected certain essential conditions, which we have our- 

 selves been able to determine only after repeated trials. 



When desirous of obtaining regeneration, we operated on active 

 and healthy and weU-nourished frogs in the beginning and middle 

 of the winter. The operations tried in summer never succeeded. 



V. — Ohservations on some points in the Economy of Stepha- 

 noceros. By Charles Cubitt, Assoc. Inst. C. E., F.E.M.S. 



In submitting the following remarks on such a familiar subject as 

 Stephanoceros, I am stimulated to offer them with some confidence 

 on the encouraging incentive held out by Mr. Gosse to " observers 

 with good instruments " in the closing paragraph of his description 

 of this exquisite form, on which he says " there are many points in 

 its economy on which we need further light ;"* and to the investi- 

 gation of certain points that are manifestly irreconcilable with, or 

 unrecorded in the descriptions of himself and others, I have directed 

 much attention ; and should these remarks fall under the notice of 

 these acute observers, I trust they will acquit me of any motive be- 

 yond a desire to eliminate a little of the light their teachings have 

 shown us to be wanting. 



I hope to show that there exists a closer relationship between the 

 aberrant and normal forms of the Rotifer a than has been hitherto 

 recognized by many who object to Ehrenberg's arrangement of the 

 Family Floscularide on less important points than those which exist 

 in support of the intuitive correctness of his classification. 



A consideration of the functions of the Trochal Disc is the first 



* ' Popular Science Review,' vol. i. 



