NOTES AND MEMORANDA. 33 



This condensation continues until at last the little masses are resolved 

 into dark hexagonal or polygonal plates, distinctly separated by light, 

 sharply-defined lines. In some the original bright central spot is still 

 perceptible, but in others it is entirely obsciu'ed by the dark chloro- 

 phyll. The separation of these now becomes more and more positive, 

 and they begin to become convex, then lenticular, and are at last con- 

 verted into free, oval, or globular bodies. When these are fully 

 formed they are said to exhibit a peculiar trembling motion, mutually 

 crowding and pushing one another, compared by Mr. Braun to the 

 restless, uneasy movement seen in a dense crowd of people in which 

 no one is able to leave his place. Whilst the process just described 

 has been going on, the outer cellulose wall of the Hydrodidyon cell 

 has been undergoing changes, becoming thicker and softer and more 

 and more capable of solution, and by the time the gonidia are formed 

 it is enlarged and cracked, so that room is afforded them to separate a 

 little distance from one another within the parent cell. Now the 

 movements are said to become more active — a trembling jerking, 

 which has been compared to the ebullition of boiling water. Thei'e 

 is, however, with this a very slight change of space, and in a very 

 short time the gonidia arrange themselves so as to form a little net 

 within the parent cell, a miniature in all important particulars of the 

 adult Hydrodidyon. The primary cell wall now becomes more and 

 more gelatinous, and soon undergoes complete solution, so that the new 

 frond is set free in its native element. As previously stated in my 

 investigations, I have never seen the peculiar motion above described, 

 the newly-formed gonidia simply separating and arranging themselves 

 withotit my being able to perceive any motion, or exactly how they fell 

 into position." 



NOTES AND MEMORANDA. 



Mr. Browning's Stage - and - body - united Microscope. — Our 

 readers will remember that we gave a short notice with a cut of this 

 new instrument which Mr. Browning has manufactured under the 

 direction of Mr. Mayall, jun. When describing it w^e spoke of " the 

 disadvantage of a monocular as compared with a binocular instru- 

 ment." This disadvantage has since been completely overcome. 

 Mr. Browning has made several of this form of microscope of the 

 binocular kind, and finds that they give perfect satisfaction. There 

 is therefore reason to rejoice more than ever at the introduction of 

 the instrument. 



Scientific Societies' Club — Although this is not a microscopical 

 subject, it is one which as fairly interests Fellows of the Eoyal Micro- 

 scopical as any other Society. We therefore do not hesitate to intro- 

 duce it to oiu* readers' notice. For some time past Mr. J. Logan 

 Lobley has been exerting himself in the post of Hon. Secretary to this 

 Institution, and he has been, we must say, wonderfidly successful. 

 At the meeting which was held by the provisional committee in 



D 2 



