ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
389 
broad) on its lower end fitting into the opening. Between the edges and 
the projecting piece which is provided with a row of concentric grooves, 
is a copper ring which is pressed into the grooves when the cover is 
screwed on. With good packing of the piston the apparatus keeps a 
pressure of 700 atmospheres for a considerable time. With phosphor- 
bronze a pressure of 1500 atmospheres could not be obtained, the 
cylinders breaking at 1100 to 1200 atmospheres. For these high 
pressures a steel cylinder must be used. The author describes several 
interesting experiments which can be made with the apparatus to show 
to what high pressure living things and cell-protoplasm may be subjected 
without being destroyed. 
Scientific Models.* — Prof. W. His pleads for the higher appreciation 
of scientific models, which he thinks as worthy of citation as printed 
documents. Thus Hochstetter should have referred in a recent criticism 
to His’s models of eye-development prepared by Ziegler. For thei’e, 
His has in visible clearness expressed his conclusions as to the complex 
relations of the different parts. 
♦ Anat. Anzeig., x. (1895) pp. 358-60. 
