332 NOTES At<D MEMORANDA. 



forms themselves, if the descriptions are sufficiently minute 

 and exhaustive, at least in the absence of figui'es of all the 

 species, for the purpose of mutual comparison and contrast ; 

 for though the differences in many cases be in themselves 

 seemingly slight, they are doubtless, in reality, none the less 

 actual and intrinsic, therefore the words emj)loyed to verbally 

 delineate those slight but characteristic differences could 

 hardly too closely follow their minutiae. Localities for nearly 

 all the species described are given — hardly requisite, indeed, 

 for a goodly number of '''common" forms — but, on the other 

 hand, of great value as regards the " rarities." No doubt 

 the work in question will be critically examined by those 

 observers in this country and abroad who have made the 

 Diatomaceee the object of special study ; and whether they 

 should find therein views to concur in or dissent from, this 

 record of painstaking research and careful study should be 

 in the hands of each specialist in this branch of microscopy. 



Action of Sulphate of Thorium on the Blood Corpuscles. — 



At a meeting of the San Francisco Microscopical Society, 

 Dr. Blake, of San Francisco, exhibited some blood obtained 

 from a rabbit after the introduction of sulphate of Thorium 

 into the blood vessels. Although the quantity used was only 

 a grain, yet the physical properties of the blood had been 

 very much altered, the blood corpuscles having entirely lost 

 their natural form and presenting indented outline with 

 numerous small highly refractory dots at the circumference. 

 This marked influence on the blood corpuscles tends to ex- 

 plain the highly poisonous character of the salt, death taking 

 place in two minutes after the introduction of the above 

 minute quantity into the circulation. It is also in accordance 

 with the law which connects the physiological action of sub- 

 stances with their isomorphous relations and atomic weights, 

 thorium having the highest atomic weight (115) of any of 

 the members of the aluminium group which its physiological 

 reactions show it to be isomorphous. — (^American Jour?ial of 

 Microscope/, May 1876.) 



Fusisporium Solani and its Resting Spores. — Mr. Worthing- 

 ton Smith writes in the ' Gardeners' Chronicle,^ p. 6.56: — 

 Fusisporium Solani is a fungus which very commonly occurs 

 on diseased potatoes in company with Peronospora infestans. 

 One is as destructive to the potato as the other, and Mr. 

 Berkeley, writing of the former in 1857, describes it as a 

 second enemy of the potato, "equally destructive with the 

 Peronospora, and, according as the two are separate or com- 



