218 CORRESPONDENCE. 



Lao Tea. — According to the Kew Bulletin^ the Laos, who live 

 in the neighbourhood of Chiengunai, Siam, do not use tea-leaves 

 for preparing infusions, but prepare them for chewing. The leaves 

 of the Camellia theifera are steamed, then tied up in bundles, and 

 buried in the ground for about fifteen days. The product is 

 termed " mieng," and is said to keep for two years or more. It is 

 reported to be almost indispensable to natives engaged in hard 

 work. 



Potato Diseases. — A disease in potatoes has made its appear- 

 ance in several districts in the Bengal Presidency, which is quite 

 distinct from that caused by the Phytophthora infestans. It is now 

 in course of being investigated locally, but Mr. G. Massee is of 

 opinion that it closely resembles the disease caused by Ferojiospora 

 trichotoma on Colocasia antiquorum (an edible corm or Yam) in 

 Jamaica. — Kew Bulletin. 



Ambergris. — H. Beauregard is of opinion that ambergris may 

 be considered as an amber-coloured calculus containing a propor- 

 tion of black pigment and some excrementitious matters. Pieces 

 extracted from the intestines of the sperm whale appear to be 

 formed by an aggregation of acicular crystals arranged in different 

 positions. If examined under the microscope, with the aid of 

 polarised light, these crystals are readily differentiated from the 

 surrounding mass by the brilliant colours displayed on revolving 

 the prism, and it is suggested that the peculiarities of structure 

 disclosed should be utilised for the rapid investigation of samples 

 suspected to be adulterated.— y(?z/^/z<^/ de Pharmacy. 



(Torresponbence^ 



Will some microscopist kindly give me a little information 

 respecting the mounting of spread diatoms ? I find, after acid 

 treating and washing the material, that when put on the slide with 

 balsam there is such a cloudiness that spoils the appearance. I 

 shall be glad to know the cause and the cure ; so will other friends, 

 I presume, as I have received several in exchanges with the same 

 objection. — John T. Neeve. 



Plant Hairs. — Examine the hairs from the flower-stalk of the 

 Cypripedium, scrape a few off the stem, and place them under a 

 I /5th in. objective, i in, o.c, and also with polariscope. They 

 are most interesting. E. S. Mattison, M.D. 



Weak Solutions. — Is it possible that solutions of coooi per 

 cent., if used for five minutes, are of any use in staining goblet 

 cells, etc. ? E;. P. 



