ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



Ill 



fixation by means of boiling water and preservation in formol-glycerin 

 is also applicable to small Arthropoda. 



Apparatus for Rapidly Cooling Paraffin.*— C. U. A. Kappers 

 describes an apparatus (fig. 24) for rapidly cooling paraffin blocks. It 

 consists of a metal box A, which has an opening B for connecting 

 with the water supply. The table C has two steps, the object being to 

 accommodate blocks of different sizes. A piece of one side D is cut 

 out so that the level of the water in the tank is just below the upper 

 surface of the blocks. When the upper surface of the paraffin has 



become sufficiently hard to bear the water, the aperture D is closed by 

 means of a glass plate. The apparatus is supported upon a basin by 

 means of four arms. 



Studying the Development of Ophiothrix fragilis.f — E. W. 

 MacBride made observations on and also drawings of living larvae. 

 Those used for sections were fixed in 1 p.c. osmic acid, followed by 

 Muller's fluid. The sections were made by the celloidin-paraffin method 

 and the procedure similar to that already described by the author in the 

 case of Echinus esculentus. It was found that the celloidin became 

 badly cracked if the sections were left drying on the top of the thermo- 

 stat for longer than 40 minutes. When it was necessary to supplement 

 the information obtained from views of the living larva? by whole 

 mounts of preserved ones, these were cleared from osmic acid by immer- 

 sion in water or weak alcohol. The vessel containing them was then 

 placed (open) inside a larger one, on the bottom of which was a layer of 

 chlorate of potash crystals, over which strong hydrochloric acid was 



* Zeitschr. wiss. Mikrosk., xxiv. (1907) pp. 254-7 (1 fig.). 



t Quart. Journ. Micr. Sci., li. (1907) pp. 557-606 (6 pis. and 4 figs, in text). 



