1890.] MICROSCOPICAL JOURNAL. 155 



A Now Motliod for Studyiiii;' tlio Eh'uu'uis and Tissues of Warin- 

 KloodiMl Annuals at tlw'iv IMiysiidogical Tcniiu'ralure.* 



By Prof. L. RANVIER, 



MKMBRE DE l'iNSTITUT, PARIS. 



The iiicthod consists in plunging the miscroscope and the prepara- 

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



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

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

 fully imbedded in parafhne, 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 tliis pvc- 

 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 w^ater because undistilled water when heated deposits calca- 

 reous matter. 



Place the microscope in the water, haying the slide only one half 

 or 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 witii the microscope will lower its temperature 2 or 3 

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

 vations lasting more than 8 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. 



Pv 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 wish to communicate a fact in general biology which appears 

 of some importance. 



Wc know tiiat 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 24 

 hours, as I have demonstrated by tlie following experiment: 



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

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

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

 oratory at a tem23erature of 10° or 15'' C. for 24 hours. Then, raising 

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

 have seen great numbers of lymphatic cells throw out auKcboid pro- 

 longations and thereby move about. 



Before raising their temperature to the point necessarv for their \'it;d 

 reactions, these cells were spherical ami immol)ile. 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. 



* 'I'ranslatcd in abstract from the yourtial eie Micrographic for April, 1890, by F. Blanchanl, M. D. 



