ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 129 



and may be rendered accessible even to strong magnifying powers if 

 placed on a glass block of suitable size. For prolonged observations 

 tbe whole object may be attached to Thomas's object-holder, with 

 arrangement for irrigation, and may be kept in the natural fresh 

 condition of life by irrigating with amniotic fluid or ^ per cent, salt 

 solution. 



By this method Prudden was able, by irrigating with the latter 

 fluid, to observe the cartilage cells in the episternum of the frog 

 for many hours, in the living and fresh condition. Under these 

 circumstances the intercellular substance appears homogeneous, 

 the outline of the cell is very clear, and the cell-protoplasm has a 

 finely granular appearance, with bright globules near the nucleus ; 

 the latter has a double contour, is penetrated internally by a number 

 of fine lines, which meet at broader internodes. In this form of 

 nucleus he could observe phenomena of movement, but could not 

 determine that any effect was produced upon these movements by 

 weak chemical reagents, by heat, or by electric currents. Under the 

 action of 1 to 3 per cent, salt solution the cells shrink back from 

 their vpalls, and are seen to be provided with numerous processes,- 

 which radiate to the walls of the cavities ; vacuoles are also formed 

 in the interior of the cells under these circumstances. When water 

 is added to the solution, the cells resume their original appearance. 

 Similar production of vacuoles under pathological conditions in cells, 

 which have in like manner the power of reverting to the normal 

 condition (Swetsky), the author believes to be explicable by an 

 increase in the density of the liquid which the tissues contain. If 

 the living episternum is irrigated with indifferent liquids and then 

 replaced, the cells appear quite unaltered at the end of nine weeks. 



In an episternum which had been excised and placed in the lymph 

 sac of a frog, the cells were found to be filled with yellow drops, 

 soluble in ether, after five days, and the cell-nuclei stained with 

 carmine. An identical degeneration of the cells, accompanied by 

 susceptibility to staining with carmine, took place when the epister- 

 num was exposed and replaced after its cells had been killed by 

 chemical reagents or electric shocks. Carmine did not stain the 

 nuclei at all in the living cartilage, neither after irrigation with 

 2 per cent, salt solution, nor after subsequent dilution of this liquid 

 with water, nor when the episternum had been restored to the body for 

 some weeks ; consequently the cells had not died. The author found 

 that even very weak solutions of iodine, and also carbolic acid solutions 

 of a greater strength than ^ per cent. — that is, solutions which are 

 actually employed in the treatment of affections of the joints — caused 

 the immediate death of the cells, so that when the tissue was subse- 

 quently replaced the degenerative processes just mentioned set in. 

 The author found that the cells of living cartilage collapsed under 

 a temperature of 53° C, in detached pieces at that of 50° C, a lower 

 temperature than that which Rollet found necessary. 



Statoblasts of Lophopus crystallinus as a Test for High-power 

 Objectives.— Areolations of Isthmia nervosa. — Dr. John Anthony 

 writes : — " I forward an object which I think will be found of value 



Scr. 2.— Vol. II. K 



