76 BOTANICAL GAZETTE [july 



Myxomycete studies. — ^Degenerating nuclei have been observed in young 

 sporangia of various ^iyxomycetes. Jahn^*^ finds that at an early stage in the 

 development of the sporangium nuclei fuse in pairs, and that the degenerating 

 nuclei are those which have failed to fuse. Preceding sporogenesis Jahn claims 

 to have found synapsis and a reduction of chromosomes- In Ceratiomyxa the 

 mature spore has four nuclei. When the spore germinates there is another mitosis, 

 and eight uninucleate swarmspores are produced from the amoeba. Swarms pores, 

 amoebae, and plasmodia seem to have the reduced number of chromosomes, 

 the 2X generation being confined to a comparatively short period in the 

 development of the sporangium. — ^Charles J, Chamberlain. 



A bacterial plant-tumor. — Smith and Townsend^' have demonstrated that a 

 gall occurring on the cultivated ^'marguerite" (Chrysanthemum frutescens) is 

 caused by a bacterium, for which they propose the name Bacterium tumejacieMS. 

 The organism w^as isolated, and in some of the experiments too per cent, of the 

 inoculations gave positive results, while the check plants remained free from 

 tumors. As the authors say, *'the number of vegetable galls known positively to 

 be due to bacteria is not very great. The discovery of a new one of undoubted 

 bacterial origin, therefore, is of considerable interest to plant pathologists, and 

 may be of some interest to animal pathologists, especially to those interested in 

 determining the origin of cancerous growths." — J. M. C. 



Rate of growth in Jamaican forests.— Shreve^^ has studied the rate of leaf 

 growth in the rain-forest of the Jaimaican mountains, and reaches the following 

 conclusions: (i) that the rate of leaf growth is very slow as compared with that in 

 tropical trees in which it has already been measured; (2) that the renewing foliage 

 of deciduous trees does not grow more rapidly than that of evergreen broad-leaved 

 trees; and (3) that the prevalence of conditions unfavorable to photosynthesis 

 and transpiration would seem to ofi"er at least a partial explanation of the slow 

 rates of growth. — J. M. C. 



Potato scab. 



^s recently published a summary of > 

 potatoes and of the methods in vogue 



vention. 



tubers 



formal dehyd 



is given of the newer treatment with formaldehyde gas generated by the heat 

 arising from the chemical action due to pouring the formaldehyde over some 



2^ Jahn, E., Myxomycetenstudien. 6. Kemverschmelzungen und Reduktions- 

 teilungen. Ber. Deutsch. Bot. Gesells. 25:23-26. 1907- 



=^7 Smith, Erwin F., and Townsend, C. O., A plant-tumor of bacterial origin- 

 Science N. S. 25:671-673. 1907. 



^^ Shreve, Forrest, Studies on rate of growth in the mountain forests of Jamaica. 

 Johns Hopkins Unjv, Circ. i907:no. 3. 31--37. 



29 Morse, W. J., The prevention of potato scab. Bull. Maine Exp. Sta. 141:81- 

 92. 1907. 



