200 THE AMERICAN MONTHLY [June 



which had been sug-g-ested to him by the presence of B. 

 coli in the bhidder. On these media the microbes g-rew 

 luxuriantly, forming- g-reyish colonies; the B. typhi abd. 

 less rapidly in fine transparent patches". In the discussion 

 Eisner said there were plenty of differential signs ; the 

 difficulty was to cultivate Eberth's bacillus when it was 

 only present in small numbers — for instance, in water, or 

 mixed with other bacteria, for example, in stools. Ewald, 

 Wolf, and Senator, all had found Eisner's method very 

 useful for the diag-nosis of doubtful cases from the stools. — 

 Brit. Med. Journal. 



BIOLOGICAL NOTES. 



Fertilization of the Gymnosperms. — A very important 

 discovery in the mode of impreg-nation in Gymnosperms 

 made by two Japanese botanists, Professor S. Ikeno and 

 Dr. S. Hirase, which was recently referred to in our pages, 

 supplies a most interesting- link between this section of 

 Phanerog-ams and the higher Cryptog-ams. Dr. Hirase 

 has discovered that in Ginkg-o bilaba, Salisburia adianti- 

 folia, impreg-nation is effected by antherozoids formed 

 within the pollen-tube. The two nuclei resulting- from 

 the final division of the g-enerative nucleus of the pollen- 

 tube are converted, before entering- the oosphere, into 

 motile antherozoids, resembling those of the higher Cryp- 

 togams, but differing somewhat in form. They are ellip- 

 soidal 82 microns long by 49 microns broad, and contain 

 in the centre a nucleus entirely surrounded by cyptoplasm. 

 The main body consists of a head composed of three spi- 

 ral coils, and a slender tail; to the former are attached 

 numerous cilia. As soon as the antherozoids have escaped 

 through the apex of the pollen tube, they enter the oosphere 

 with a rapid twisting motion. Attraction spheres were 

 observed accompanying the final division of the pollen-tube 

 nucleus. Professor Ikeno has made a similar observation 

 respecting the mode of impregnation in another Gymno- 

 sperm, Cycas revoluta. The antherozoids are here some- 

 what larger than in Ginkgo ; the main body is composed 



