L919J EXPERIMENT STATIOS RECORD. M7 



AGRICULTURAL BOTANY. 



The unification of American botany, Q. R. I.v.mw (Botenee, n. *rr. ','> 

 (1919), No. 1267, pp. 839S45).— The author presents an argument for broaden- 

 ing the teaching of botanical Bubjecta so as t<» produce nol merely -i iaiists 



but broad-gauge men of wide perspective. 



Note on the technique of solution culture experiments with plants, I». It. 

 Hoaqland (Science, n. ser., .','.) {1919), No. t267, pp. 360 S62). attention Is 

 called to the desirability of better technique in experiments with plants grown 

 in solutions in order that the results obtained by different Investigators may 

 In- comparable. Conclusions arc said to be based ordinarily on the concentra- 

 tion of the solutions as originally prepared, but experiments have shown that 

 the composition of the solutions may ho so changed In a few hours as to rep- 

 resent an entirely different solution. In one case barley plants -i\ weeks old 

 placed In a solution containing 100 parts per million of nitrate absorbed every 

 trace of nitrate from the solution in less than 72 hours. Attention should also 

 be given to optimal conditions of light and temperature or allowances made for 

 suboptimal conditions. The author claims that each set of conditions should be 

 tested by actual analysis of solutions and plants, and the results interpreted In 

 terms not of the original solutions alone but also in terms of total supply and 

 the varying conditions of the solutions in the periods between chan 



The dendrograph : A new instrument for recording growth and other varia- 

 tions in the dimensions of trees, D. T. MacDougal (Carnegie Inst. Washington 

 Year Book, 17 (1918), pp. 59, 60). — Two forms are described of a special device 

 for measuring growth as employed with trees. 



Plant genetics, J. M. and M. C. Cotjlteb (Chicago: Univ. Chicago Press, 1918, 

 pp. IX+214, figs. 40). — This is a textbook on genetics to meet the requirements 

 of students who are in the last undergraduate or the first graduate year and 

 who expect to follow botany as a profession or who wish to appreciate the a 

 nificance of current work In genetics. 



The chromosomes, their numbers and general importance, t). WlRQI 

 (Compt. Rend. Lab. Carlsbcrg, IS (1917), No. 2, pp. til 575, figs. j6).— Since 

 1014 the author has collected information regarding chromosome numbers In 

 the vegetable kingdom, this work dealing mainly with the theoretical aspects 

 of the subject. 



The nucleus Is regarded as of phylogenettcally younger origin than is the 

 cell as a whole, indicating an advance In its differentiation. In EBntorrhisa the 

 spores possess a nucleus free from chromatin, and free, split chromosome-like 

 bodies appear in the cytoplasm. Chromosome numbers In higher plants can as 

 a rule be resolved into the prime factors 2 and 3. more rarely 6 and 7. Tim 

 most frequently occurring chromosome numbers by far are 8 and 12. Altec 

 this in order come 16, 6, and 0. The species (in higher plants) of a systematic 

 group have chromosome numbers which are related by simple multiples of the 

 same cardinal numbers and enter Into an arithmetical p ion. The 



formula for the Chenopodiacea- appears to be x=3n (n>2), A certain regu- 

 larity appears In such families as the Composite. The chromosome numbers 

 for the groups Ileliantheoe and Anthemidea> are represented by x*=Sn and x=Ioi, 

 respectively. 



Chromosome number is thought to afford weighty evidence as regards genetic 

 relationships. Apogamy is thought to be due to hybridization. In Callitriche 

 verna the reduction division of the pollen mother cells originates heterochromo- 

 somes, which can not be homologized with those of animal origin. The mottled 

 coloring of Hamulus japonicus alhomamlata Is transmitted only through the 



