SCIENCE-GOSSIP. 



2og t 



a fixed tube and placed at an angle of about 45°, 

 and a distance of about 10 or 12 inches from the 

 surface to be photographed. Time, 40 seconds. 



Nitrifying Germs. — In the course of a paper 

 which was read at a recent meeting of the 

 American Microscopical Society, Dr. M. A. Yeeder 

 refers to the necessity of purifying potable waters 

 by the nitrifying process. It has been discovered 

 recently that there is an antagonism between 

 disease germs and what are known as nitrifying 

 organisms, which produce nitrites and nitrates in 

 the soil. Advantage has been taken of this to 

 institute an intermittent process of filtration. Water 

 containing the bacteria that it is desired to destroy 

 is allowed to run into a filter composed of sand, and 

 instead of being drawn oft" immediately is allowed 

 to stand for a sufficient length of time to permit 

 the destruction of the disease germs by their 

 natural foes. 



The Orange Mite. — The greenhouse serves as 

 a prolific hunting-ground for the microscopist, 

 one of his most frequent acquaintances being the 

 often abudant greenhouse mhes.Tctranychus telarius. 

 Now that the orange season is coming on it may 

 be of interest to draw attention to a mite which 

 infects the orange, and which is 

 genetically allied to its green- 

 house relative. To assist those 

 who may desire to seek for this 

 little creature, which is known as 

 Tetu maculates, the six- 



spotted mite of the orange, we now 

 append some enlarged drawings of 

 it, in which .1 represents the mite 

 as seen from above, b the tarsus, 

 c the rostrum and palpus, and d 

 the tip of the palpus. 



Practical Microscopy. — In a 

 lecture on this subject, delivered 

 to the Chemists' Assistants' Asso- 

 ciation last month, Mr Martin 

 LCole gave many useful hints 

 uing on the technique of the 

 cutting, staining and mounting of 

 vegetable tissues. Having cut 

 some sections of the stem of a 

 plantain, he proceeded to mount 

 some, unstained, in glycerine jelly, 

 and some, double-stained with acid green and 

 carmine, in Canada-balsam. The glycerine jelly 

 was made by dissolving one ounce of gelatine in 

 six ounces of water, adding four ounces of glycerine 

 and a little creosote to preserve it. 



.-. Glycbrine. — Although alkaline 

 has been recommended for several 

 ■:s in micro-technique, it does not appear to 

 be generally known how serviceable it is as an 

 extemporary mountant in vegetable hist 

 Mr. \V. Kirby. 1 L.S., finds, says the " Phar- 

 maceutical Journal. " that the mixture best adapted 

 neral use is composed of gl) 

 ,, distille! ad a-half ounces, 



vilution of potash, B.P . half-ounce This com- 

 bines the rcfringent property of the glycerine with 

 the clearin, I the caustic potash, and it 



has the gnat advantage that the 

 swelling act he potash is considerably 



restrained 



IAI \>T A M I ; 



outes a su, . Bai II 



- 

 -copical Journal " Neither the Eocene nor 



the Pliocene diatoms in England have yet received 

 the attention their importance merits. Dr. Edwards 

 has given his attention to the matter, and has 

 obtained from the London clay, fossil forms of 

 Coscinodiscus astemmphahis, little discs covered with 

 hexagonal markings and ring-like forms, which he 

 suspects to be Melosira sulcata. The cast of a 

 Triceratium in pyrite, and the silicious shell of 

 Stephonopyxis funis were also discovered. This 

 opens up an interesting field for investigation, for 

 as Bacillaria are in the London Clay, it is evident 

 that they should be traceable low down in the lower 

 Eocene in geologic time. 



Drinking-Water and the Microscope. — A. 

 few years ago chemical analysis was relied on to 

 determine the fitness of water for drinking, and 

 sufficient dilution of poisonous matter was regarded 

 as making it harmless. This is changed. The 

 problem is now looked upon as a biological rather 

 than a chemical one, and the purity of water 

 is judged by the character of the organisms it may 

 contain, the fact being recognized that even the 

 minutest possible quantity of foreign matter, if it 

 be a disease germ, may be sufficient to start an-, 

 epidemic. The danger consists not in the quantity 

 of such organisms, but in their 

 power of growth under certain con- 

 ditions. Typhoid fever, cholera, 

 and certain forms of dysentery, 

 are the chief diseases whose in- 

 fection, it is generally admitted, ' 

 can live in water; but Dr. M. A. 

 Veeder, of Troy, states that during 

 the last ten years he has main- 

 tained that the term "malaria," 

 meaning bad air, is a misnomer, 

 and that diseases of this class are 

 very largely, if not exclusively, 

 conveyed in water. Admitting 

 this, drinking-water brings two 

 classes of danger. Water taken 

 from near human habitations may 

 be contaminated with typhoid and 

 diarrhoea germs from excreta, and 

 that from virgin soil and undrained 

 districts may bear the germs of 

 malaria. In many localities safe 

 water can only be had by purifica- 

 tion, and for this an intermittent filtration — taking 

 advantage of a recently discovered antagonism 

 between what are known as nitrifying organisms 

 and disease germs — may be better than sand filtra- 

 tion alone; the water being allowed to stand in 

 the filter until the introduced nitrifying organisms 

 have had time to destroy their foes. 



Inter-relations of Insects anu Yeasts. — 



The inter-relations of insects and yeast have, 



according to "Nature," been ably demonstrated 



b I " Amedeo Berlese. Tor the purposes of his 



investigations he used a large glass jar, well closed 



and carefully sterilized, inside which was hung a 



bunch of grapes that had also been sterilized by 



successive washing and immersion in carbon 



dl itilphlde and boiling water. Connected by 



glass lubes with this jar were two other jars, one 



on each tide, :>ll of which were carefully Bterili; 1 d, 



1 arranged that air could penetrati thi system 



plug ol itei [lized cotton. Foui teen "I 



mblnatl in wi 1 e prepared, and In one was 



pla< ed II 1 d mb itana , sui b as bai V. ol 



e, barl ol vim , and oil ! iimilai substam e ■ 



ii nd, 1 hese were lirsi 



nge Mite. 



(t-macitlatus 



