136 



the stage where it had orange spores, in which state it was extremely likely 

 to be disintegrated ; |the green parts were untouched by the iodide, but the 

 parts which had become orange were rendered more brilliant, and the preser- 

 vation, as far as it had gone, seemed very good. The specific gravity of 

 such a weak solution would be, as nearly as possible, the same as that of 

 water.* 



Mr. Michael inquired if Mr. Ingpen had any experience with other kinds 

 of Algse, such as Closterium f The two things easiest of all to preserve had 

 hitherto been Yolvox and Micrasterias, but he should be glad to know if 

 this new medium had been tested with Closterium. There were some 

 extremely fine foreign slides which showed Volvox very well indeed, but 

 other kinds of Desmids were not so well preserved. 



Dr. Matthews said that Dr. Cooke relied very much upon mounting these 

 plants in plain water. Had Mr. Ingpen tried that plan ? 



Mr. Ingpen said he had mounted specimens of Desmids in plain water, 

 but had never succeeded well — there had always been a great deal of 

 shrinking. Dr. Cooke said truly that if they wanted to name Desmids 

 they must get rid of the endochrome ; but in this case he wanted to see and 

 preserve the endochrome. The action upon Closterium would undoubtedly 

 be greater than on Volvox; but then it varied very much in Volvox. If 

 they got a sterile specimen they might find it unaltered for months after- 

 wards, but if it were developing, that would be a very different matter. 

 Another objection to plain water was that there always seemed to be some 

 degree of alteration in the tissues, as if by a gradual death. To preserve 

 these objects effectually they should be killed suddenly. He thought that 

 the success of the process depended very much upon the exact stage in 

 which the specimens happened to be. 



Mr. Waddington said he did not find the quantity named strong enough to 

 kill these objects. One thing, however, struck him, and that was how 

 peculiarly refreshing it seemed to hear of so simple a solution after some of 

 the heroic mixtures which had of late been recommended. He thought that 

 the iodide should be as pure as possible, for he believed that in what was 

 ordinarily sold it was usual to add some alkali. 



Votes of thanks to those gentlemen who had made communications to the 

 meeting were unanimously passed, and announcements of meetings and 

 excursions for the ensuing month having been made, the meeting terminated 

 with the usual Conversazione, at which the following objects were ex- 

 hibited : — 



Pappus of Lettuce seed Mr. F. W. Andrew. 



Desmids, &c, &c, a gathering from Keston ... Mr. E. Dadswell. 

 Young Locust (Edipoda cruciata, one day old Mr. F. Enock. 

 Amoeba difiuens, &c, in a growing slide, \ Mr> w Goodwin. 



showing different stages of development J 

 Stentors ... ... ... ... ... ... Mr. H. R. Gregory. 



Objects shown by coloured light (Chromato- ") M T D H d 

 scope) ... ... ... ... ... j 



* The success of this method is doubtful when there is much orgauic matter or iron 

 in the water. — J. E.I. 



