384 SUMMARY OF CUREENT RESEARCHES RELATING TO 



MICROSCOPY. 



A Study of the Forms Assumed by Drops and Vortices of a 

 Gelatinizing Liquid in Various Coagulating Solutions. — Emil 

 Hatschek {Proceedings of the Royal Society, Series'- A, 95, 303). The 

 investigation to be described in the present paper was begun with 

 the object of testing experimentally some suggestions made by Professor 

 d'Arcy Thompson. The substance of these suggestions is that many 

 organic forms show symmetries corresponding closely to those of 

 vibrating bodies of similar shape, and that many others recall very 

 strikingly the shapes exhibited transitorily by splashes and by vortices. 

 In the usual method of producing vortices, causing drops of a coloured 

 liquid to fall, or jets of it to emerge, into another with which it is 

 completely miscible, the various stages of the phenomenon succeed one 

 another with great rapidity, so that either unusually acute observatiou 

 or instantaneous illumination and photography is required to isolate 

 any particular one. Even apart from this difficulty, the procedure has 

 a serious defect when viewed as a method of imitating organic form, 

 inasmuch as organisms cannot possibly consist of liquid alone, but are 

 either colloidal solution enclosed in membranes, or possess the physical 

 properties of gels. 



It appeared to the author that it would be possible to obtain 

 permanently various stages of the vortex on the one hand, and on the 

 other, to approach much more closely to nature in respect of secondary 

 features of possible importance by using a gelatinizing sol (e.g. a 

 suitably coloured gelatine sol), and producing with it drops or vortices 

 in one of the numerous solutions which promote the setting of gelatine 

 sols, or cause hardening of gelatine gels. Apart from the" possibility of 

 arresting the vortex at any given stage by a suitable choice of solution 

 and concentration, this procedure seemed to promise results not obtain- 

 able with liquids alone. It may be said in anticipation that all these 

 expectations were fully realised, and that the experimental technique 

 was gradually perfected. 



The paper is one of considerable interest to microscopists, particu- 

 larly those engaged in biological investigation ; but it must be read in 

 full to appreciate the argument. No abstract can possibly give a 

 proper idea of the experiments described. J. E. B. 



An Investigation of Extreme Ultra-violet Spectra, with a 

 Vacuum Grating Spectograph.— J. C. McLennan, F.R.S. and R. J. 

 Lang, M.A., University of Toronto {Proceedings of the Royal Society, 

 Series A, 95, 258). The results of some studies with quartz and 

 fluorite spectographs have already been published ; and in the present 

 communication an account is given of some preliminary observations 

 made with a vacuum grating spectograph. The results obtained show 

 that it is quite feasible to investigate with comparative ease spectra 

 including wave-lengths as short as 584 angstrom units. J. E, B. 



