946 RECORD OF CURRENT RESEARCHES RELATING TO 



the result of this would be that an error of 10 jier cent, would have 

 the probability of one-fifth, w would fall to 2 per cent, if the count- 

 ing were extended to 1250 or 100 squares, and the probability of an 

 error of 4 per cent, would be one-fifth. An error of 6 per cent, would 

 have the small probability of only one-twenty-third, and an error of 

 10 per cent, might be expected to occur once in 1400 cases, which is 

 as good as being excluded altogether. 



Moreover, the limitation of the probable error to 1 per cent, would 

 be ensured by extending the number coixnted to a total of about 5000, 

 which, under the conditions here assumed, would correspond to the 

 contents of the whole square millimetre. In this case, therefore, the 

 mean value may safely be assumed as true to within 2 to 3 per cent., 

 because an error of 4 per cent, would occur once only in 160 cases. 



This method of judging of the exactness of the results is capable 

 of being applied to various other scientific investigations of the same 

 kind. 



Cheilo-angioscopy.* — This name is applied by Dr. C. Hueter to his 

 new process for the direct observation of the circulation in the human 

 subject. 



The apparatus consists of a frame, something like that used by 

 photographers, for supporting the head of the jiorson under observa- 

 tion, and having attached to it a stand on which a microscope and 

 lamp are supported. The patient's lower lip is drawn out, and fixed 

 with clips on the stage of the microscope : a strong liglit is then 

 concentrated on its inner surface by means of a condenser, and it is 

 examined by an objective of low power, the superficial vessels which 

 can be seen even with the naked eye being brought into focus. 



The vessels look, at first, as if filled with an opaque red injection ; 

 but with a little practice and careful focussing, the observer is soon 

 able to make out the movement of the blood stream, and even to dis- 

 tinguish the red and the colourless corpuscles. The epithelial cells 

 of the mucous membrane, and the apertures of the mucous glands, 

 may also be seen. 



By the application of slight pressure to the lip, the phenomena of 

 venous stasis may be studied : it is also easy to observe the efiect of 

 cold, by touching the lip with ice, or that of innocuous reagents, such 

 as glycerine or ammonia. The various pathological conditions of the 

 circulation, characteristic of certain diseases, are also easily studied 

 with complete accuracy. 



Hueter remarks that the pathological observations he has already 

 made by means of cheilo-angioscopy, prove conclusively the import- 

 ance of the new process : a good deal of practice is, however, 

 necessary, before it can become clinically useful. 



Value of the Microscope in Law and Medicine.— Dr. E. H, Ward, 

 of Troy, N.Y., in his able presidential address t at the opening 

 meeting of the American Society of Microscopists, held at Buffalo in 

 August last, deals at some length with the legal uses of the Micro- 



* 'Cblt. med. Wiss.,' Nos. 13 and 14 (1879). 

 t ' Buffalo Daily Courier,' Aug. 20, 1S79. 



