238 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



diameter 7 in. There is a perforated platform about 2 in. from the bottom 

 in which any flask of the size of 1 litre can be placed. About 1 in. from 

 the top there is a circular ring which serves to support an enamelled 

 funnel used for hot-water filtration. By conducting the filtration 

 entirely within a heated chamber the difficulty of keeping the neck of a 

 hot- water funnel sufficiently Avarm is entirely obviated. The apparatus 



is arranged for use with an ordinary Bunsen 

 burner, but can be worked efficiently l)y an Etna 

 l)low-lamp. 



M Collecting and Preparing Cyanophycese.* — 



N. L. Gardner removed the coarse impurities by 

 the decantation method. The material was then 

 placed in jars in the shade until it had crawled to 

 the centre in a mass. When placed in direct sun- 

 light the mass, owing to the formation of gas, 

 floats to the surface. From the margin new clean 

 growth is formed and this is removed with scissors. 

 In order to get the filaments into a small 

 mass for imbedding they are repeatedly sucked 

 into and forced out of a pipette until thoroughly 

 broken up. On standing for a few hours in the 

 shade they will be found to have crawled together 

 again into a single mass, and in this condition may 

 be killed and imbedded in paraffin for section- 

 ing. Small species scattered among fine debris 

 were cleansed by centrifuging and then decanting 

 off the supernatant fluid and filtering. After 

 the material thus obtained has been washed, it may be dehydrated in a 

 dialyser. To sections of prepared material the author prefers uncut tissue, 

 for all that is demonstrable by the former procedure can be more easily 

 attained from the staining and mounting of uncut cells. The cells may 

 be killed, stained, and fixed to the slide with albumen if not sufficiently 

 gelatinous in themselves, e.g. OsciUatoria. In order to kill and separate 

 the cells a strong iodo-potassic iodide solution is advised ; 10-30 minutes 

 or longer will not hurt the plants. The material is then washed with 

 05 p.c. alcohol and afterwards with water. The cells break apart and 

 adhere well to the slide. Besides iodo-potassic-iodide, i)5 p.c. alcohol, 

 Flemming's and Hennann's solutions, sublimate, 1 p.c. chromic acid, and 

 iridium chloride were used as killing and fixative agents. A very long 

 list of staining reagents is given, most of them being anilin derivatives, 

 though the varieties of carmin and of htematoxylin are also included. 

 A variant of the Ehrlich hematoxylin gave good results. In this 

 Griibler's hsmatin was substituted for hematoxylin. This solution was 

 effective as a simultaneous killing and staining agent, and differentiated 

 well after a variety of fixatives. 



(2) Preparing Objects. 



Studying the Vitellus.f — H. Dubuisson removed the organs from 

 Hving animals, using an anesthetic when necessary. The fixative chiefly . 



* Univ. California Publications (Botany), ii. (1906) pp. 237-96 (6 pis.), 

 t Arch. Zool. Exper., v. (1906) pp. 153-402 (52 figs.). 



Fig. 46. 



