1800.] MICROSCOPICAL JOURNAL. 155 



A New Motliod for Studying the Elements {ind Tissues of Warm- 

 Blooded Animals at their Physiological Temperature.* 



By Prof. L. RANVIER, 



MRMBRF. DE l'iNSTITUT, PARIS. 



The method consists in plungin<y the miscroscope and the prepara- 

 tion to be examined intg a vessel of water warmed to 36°-39° C. 



Tlie microscope should be of simple construction, and, of course, 

 an immersion objective U> required. The object to be studied is care- 

 fully imbedded in paraffine, so that the water cannot penetrate to it. Ex- 

 amine, and select the interesting point as in an ordinary microscopic 

 examination. 



Warm the objective in dry air to about 40° C. Without this pre- 

 caution, a mist, more or less dense, will form on the surface of the 

 lenses. 



By the side of the microscope on the work-table, place a glass ves- 

 sel containing distilled water warmed to 40° C. It is necessary to use 

 distilled water because undistilled water when heated deposits calca- 

 reous matter. 



Place the microscope in the water, having the slide onlv one half 

 ot one centimetre beneath the surface. A thermometer should be placed 

 in the water. The contact of the water with the sides of the contain- 

 ing vessel and with the microscope will lower its temperature 2 or 3 

 degrees, /. <?., to about the temperature of living animals. For obser- 

 vations lasting more than S or 10 minutes, it is necessary to add suffi- 

 cient hot water to keep the temperature at 37° or 38° C. For brief ob- 

 servations this is not necessary. 



If bubbles arise between the lens and the cover-glass, they may be 

 removed with a pencil. 



By these simple means the author has been able to make more obser- 

 vations in a month than in twenty years with the old apparatus, among 

 them, for example, watching the division of lymphatic cells in mam- 

 mi fers. 



I intend to review, complete, and extend these observations. Mean- 

 while I v,ish to communicate a fact m general biology which appears 

 of some importance. 



We know that in mammifers dead for twenty-four hours, the tissues 

 no longer present physiological reactions. Nevertheless, anatomical 

 elements separated from the animal before death are still living in 34 

 hours, as I have demonstrated by the following experiment : 



From a rabbit killed by decapitation I have taken a drop of peritoneal 

 lymph, by means of a pipette sterilized by heat, placed it in a portable 

 humid chamber, and covering it with paraffine, have kept it in the lab- 

 oratory at a temperature of io° or 15° C. for 24 hours. Then, raising 

 the temperature to 38° by means of the above described hot bath, I 

 have seen great numliers of lymphatic cells throw out ama4>oi(l pro- 

 longations and thereby move about. 



Before raising their temperature to the point necessar}^ for their vital 

 reactions, these cells were spherical and immobile. They were then 

 in a condition of latent life, a sort of hibernation ; but after 24 hours 

 they revive, on the application of the proper degree of heat, 



♦Translated in abstract from the jfournai de Micrographie for April, 1890, by F. Blanchard, M. D. 



