Journal of Applied Microscopy. 277 



is always a longitudinal division of the chromosomes and consequently only a 

 numerical reduction. SchatTner finds a transverse division and consequently a 

 qualitative division (reduction division) in the first division of the nucleus in the 

 embryo-sac of Li/iiim. Belajeff believes that a reduction division occurs in the 

 second division of pollen mother cells. Calkins report.s. a reduction division in 

 ferns. Mr. Stevens has studied this problem in the ferns, Siolopeiidriuni vitlgarc, 

 Cystopteris fragills, and Ptcris aquilina. A weak solution of Flemming's mixture 

 is recommended for fixing. It may be used hot or cold. Chloroform was used 

 to precede the paraffin. The safranin, gentian violet, orange combination gave 

 the most satisfactory staining. The summary is about as follows : in the first 

 division of the spore mother cell, the spireme thread splits longitudinally and 

 then segments into one half the usual number of chromosomes. The daughter 

 chromosomes are short and thick and in their form resemble tetrads, but there is 

 no transverse division. The daughter chromosomes begin to separate, some- 

 times at the end and sometimes in the middle, thus forming double rods or ring- 

 shaped chromosomes. In the daughter nuclei, the chromosomes fuse into a 

 single nuclear thread. In the second division this thread splits longitudinally, 

 and then segments transversely as in the first division. It follows that there is 

 merely a reduction in the number of chromosomes and not a reduction division. 

 The writer thinks that Calkins' figures lack important stages and do not prove a 

 reduction division. No centrosomes or multipolar spindles were found. 



c. J. c. 



Polariscopeand Bacterial Cultures. Fuenfstueck N. J. C. Muller, in a long contribution 

 Beitrage z.Wissenschl. Boi.,3: i-i76,pl. 1-39. on certain pathogenic bacteria, discusses 



the question of morphology and impure 

 cultures of typhoid, diphtheria, tuberculosis, cholera, and Bacterium monanchae. 

 Supposedly pure cultures of those gave way to other predominating forms after 

 longer or shorter periods, with reduction in size of some species. A polariscope 

 test in ordinary gelatin tubes, with mixed cultures obtained from water, revealed 

 certain characteristic differ ences. Of 175 zooglote examined, 115 did not change 

 the optical relations on the surface. Forty-seven had the axis of greatest elas- 

 ticity tangential, 13 radial. L. H. Pammel. 



RECENT LITERATURE. 



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