PKOGKESS OF MICROSCOPICAL SCIENCE. 
171 
founded by M. Coste, wliich has already yielded various importan t 
scientific results. 
Effects of Concentration on the Movements of White Blood- 
corpuscles. — A very interesting paper recording experiments on the 
blood of the frog and newt, is that of Herr R. Thoma, which appears 
in Yirchow's 'Archiv.'* It has been abstracted in the 'Medical 
Eecord' of December 30, 1874, by Dr. W. Stirling. Herr Thoma 
divides his experimental inquiries into three sections : 
1. Influence of the Concentration of the Surrounding Fluid on the 
Amoeboid Movements of the Colourless Blood-corpuscles removed from the 
Body. — Blood of the frog, placed in a gas-chamber, and from which 
water was removed by the passage through it of a stream of air, 
showed that, in the portion of blood poor in water, the number of 
round, motionless, colourless corpuscles surpassed considerably the 
number of those showing changes of form. In blood in which the 
quantity of water was increased, the greater number of the colourless 
corpuscles showed the branched forms, such as are produced by the 
flowing movement of protoplasm. These corpuscles which adhere to 
the cover-glass are more spread out, show clearly three or four nuclei, 
and bear more richly branched processes, oftener contain vacuoles, and 
show more lively changes of form than those floating free in the fluid. 
This is, without doubt, due to the action of the surface, and is pro- 
duced by strong adhesion of the body of the cell to the surface of the 
glass. This property also belongs to a series of other solid bodies, 
and also to the intima of the vessels. The white blood-corpuscles 
become more sluggish in their changes of form with increase in 
the concentration of the fluid, and the greater number change into 
rounded cells, which sometimes have fine processes on their surface. 
This is not due to death of the corpuscles, for on increase in the 
quantity of water they again become lively in their movements, and 
resume the properties of freshly-drawn white blood-corpuscles. These 
observations were made in the blood of Bana temporaria and esculenta ; 
but the same is also true for that of Salamandra maculosa and Triton 
cristatus, and also for that of warm-blooded animals ; at least for the 
guinea-pig and dog. Under the influence of water, the contents of 
the white corpuscles may be increased four times, and this can only be 
regarded as an imbibition phenomenon. 
2. Experiments on Colourless Corpuscles circulating in the Bloody 
produced by injection of water into the circulation of the frog. — 
Besides unchanged colourless corpuscles, there are a large number 
which show forms such as can be produced in blood under the influence 
of water outside the body. Those which lie upon the walls of the 
vessels exhibit very lively changes of form. In an opposite experi- 
ment, frogs were exposed for several days to evaporation. Microscopic 
observation showed that in the tongue, under these conditions, no 
amoeboid movements were to be observed in the corpuscles circulating 
in the blood, and also in those touching the walls of the vessels ; and 
the injection of a 3 per cent, solution of common salt into the veins 
showed that increase of the quantity of salts acted quite in a similar 
* Vol. Ixii. Heft I. 
VOL. xm. ^ 0 
