ZOOLOGY AND BOTANV, MICliOSCOPV, ETC. 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 Including' Cell-contents. 



Chromoplasts.* — W. Rothert has made an exhaustive study of 

 chromoplasts, and finds that thej are common in the vegetative organs 

 of plants living in warm regions, being found in 42 famiUes embracing 

 all classes of vascular plants. They are irregularly distributed in the 

 plant and their presence is not constant. They occur in any part of 

 the living tissues, to which they impart bright colours, but the latter 

 may be much modified by red cell-sap or by coloured membranes. The 

 pigment floats freely in the cell-sap, either dissolved in a minute globule 

 of oil or in plastids'which would otherwise be colourless. In the case 

 of one saprophytic orchid, pigment-crystals have been found. There 

 are intermediate forms between chromoplasts and leucoplasts, so that 

 chloroplasts, leucoplasts, and chromoplasts appear to form the end links 

 of a complete series of plastids. Chromoplasts arise either in the young 

 plant or later on, from either leucoplasts or chloroplasts, to which they 

 may be regarded as morphologically equal. They contain karotin, a 

 yellow pigment, and traces of chlorophyll, and are usually dependent 

 upon light, becoming either leucoplasts or chloroplasts in the shade, 

 although thev also frequently occur in darkness. They may likewise 

 develop under the influence of certain pathological conditions brought 

 about by insects or fungi, and it is not unusual to find them in the 

 neighbourhood of nectaries, hydathodes, or stomata. 



Chromosomes in Triticum and JJgilops.f— W. Bally has studied 

 the chromosomes in Triticum and jEgilops, and finds that Triticum 

 dicoccoides and T. vulgare agree in having eight haploid chromosomes. 

 j^gilops ovata, on the other hand, from which bastard species of Inti- 

 cum may be formed, has sixteen haploid chromosomes. 



Structure and Development. 

 Veg-etative. 



Histologic Differences between Biota and Thuja.t—F. Hollen- 

 donner contributes a note upon the stems of Biota and r/?i{/^?, and 

 points out that, while the structure of the wood is very similar in both, 

 there are also marked differences. In Thuja the wood is soft and 



* Bull. Internat. Acad. Sci. Cracovie, ser. B, No. 4 (1912) pp. 189-336. 

 t Bar. Deutsch. Bot. GeselL, xxx. (1912) pp. 168-72 (1 pi.). 

 X Ber. Deutsch. Bot. Gesell., xxx. (1912) pp. 159-62 (1 pi.). 



