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PKOGRESS OF MICROSCOPICAL SCIENCE. 



The Potato Disease. — Mr. Berkeley, writing to the ' Gardeners' 

 Chronicle,' says : — Since the meeting of the Linnean Society, of 

 which a report was given in the ' Gardeners' Chronicle, March 25, 

 1876, Mr. Smith has forwarded to me several slides containing 

 specimens of the organisms he found at Chiswick in 1875. Having 

 examined, them very carefully, I think it but justice to state what I 

 have observed. 1. The oogonia seated on thick, often flexuous threads, 

 with a septum beneath the oogonium which is sometimes carried far 

 down the thread. 2. Many instances in which the oogonium is pro- 

 duced in the middle of the thread, with a septum at either end, calling 

 to mind the figure of Montague's Artotrogus. In several instances 

 a process terminated the oogonia, as if the thread was to be produced 

 so as to leave the oogonium in the centre. 3. In one oogonium I 

 found an echinulate body, quite as strongly echinulate as in the best 

 specimens of Artotrogus. 4. The so-called antheridia produced on 

 delicate threads, quite distinct from those of the oogonia, and not 

 separated by a sej)tum. The form of the antheridia is exactly what 

 Smith has figured. 5. The antheridia in contact with the oogonia, in 

 one instance the wall of the oogonium being perforated, as if by the 

 act of impregnation. I cannot, however, speak more positively on 

 this point. 6. Abundant Peronosjiora ; threads and spores mixed 

 with the oogonia and antheridia. Of course Mr. Smith's interpreta- 

 tion of what he has seen is subject to criticism, but his good faith is 

 so far confirmed by his specimens that criticism should be very 

 guarded and gentle. If I may exj)ress my own opinion, I believe 

 that all these objects belong to one category, and if so, I should be 

 ready to receive De Bary's Phytophthora (plant pestilence) as a good 

 genus, difiering in several respects from Peronospora. — From the 

 ' Gardeners' Chronicle,' p. 436, 1876. 



The Secreting Organs of the Alimentary Canal in Insects. — In Blaita 

 orientalis, the common cocki'oach, M. Jousset has recently been 

 following out the course of the digestive system,* and the following 

 are the principal results at which he has arrived. The secretion of 

 the salivary glands, and this alone, is able to convert starchy matters 

 into glucose. The gastric cseca secrete a yellowish liquid, feebly but 

 distinctly acid, which dissolves coagulated albumen, casein, and fibrin. 

 The albuminoids are not merely dissolved, but actually converted into 

 peptones. In addition to this solvent property, the liquid in question 

 is capable of emulsifying fatty matters. It seems, in short, to 

 combine the properties of the gastric juice of the higher vertebrates 

 with those of the pancreatic fluid. The intestinal portion of the tube 

 does not appear to take any part in the digestive function ; the pej)- 

 tones, oily matters, and sugar, undergoing absorption before the food 



* See ' Comptea Reudus,' Jan. 3; and 'Acad.,' Feb. 12. 



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