610 



SCIENCE 



[N. S. Vol. XLII. No. 1087 



Italian: Eegole Internationali della Nomen- 

 clatura Zoologica. Translated by Professor 

 F. S. Monticelli, and published by Luigi 

 Niecolai, Florence, Italy, 1914. Price 5 lira. 

 Several unsuccessful attempts have been 

 made to obtain a reprint in English, but the 

 outlook for sale has been so indefinite, or other 

 points have arisen, so that publishers have not 

 been inclined to undertake the work as a busi- 

 ness venture. Finally, in order to make it pos- 

 sible for zoologists to obtain a copy of the rules 

 to date, arrangements have been made for a 

 mimeographed edition of all the rules, with 

 cross references to the opinions, and with an 

 appendix containing summaries of the opin- 

 ions No. 1 to No. 56. 



This mimeographed edition is issued by T. O. 

 Smallwood, 3216 N Street, Washington, D. C, 

 price per copy 50 cents, plus 10 cents postage. 



C. W. Stiles, 

 Secretary to Commission 



GERMINATING POLLEN 



To THE Editor of Science: In the past, a 

 number of requests have come in asking for 

 the method employed by this station in deter- 

 mining the germinability of pollen of decidu- 

 ous tree- and bush-fruits. Others who are in- 

 terested in this matter will find the following 

 method useful. 



Mature pollen, either directly from the 

 anther, or that which previously has been col- 

 lected and stored, is used. Van Tieghem cells 

 or 10 X 20 mm. moist chamber rings are fast- 

 ened to ordinary microscope object slides by 

 means of soft paraffin, employing as little as 

 possible of the latter, and yet secure a water- 

 proof joint. Put one or two drops of water 

 into the cell and at two or three points about 

 the upper edge place tiny drops of vaseline. 

 This is better than the smearing of the entire 

 circumference, since it serves as well to hold 

 the cover in place and does not exclude air. 

 Next place a small drop of the germinating 

 medium in the center of a cover glass having 

 a diameter somewhat greater than that of the 

 cell. We employ 22 mm. squares. If the 

 medium tends to spread over the glass, spread 



very thinly with vaseline and wipe with a dry 

 cloth until the vaseline apparently has been 

 removed. Sow the pollen grains evenly and 

 sparingly over the surface of the drop by 

 means of a needle or camel's-hair brush. If 

 the latter is used hold it above the drop and 

 tap lightly to scatter the pollen. Pollen may 

 be used directly from the expanded anther by 

 touching the latter to the germinating medium. 

 Quickly invert the cover, place over the cell, 

 and press it down gently, having the drop of 

 germinating medium approximately in the 

 center. A temperature of 22° to 25° Centi- 

 grade is best. 



The germinating medium is the most im- 

 portant item. It may be necessary to vary its 

 composition for the several varieties of fruits 

 or even for the same variety, depending upon 

 prevailing environmental conditions under 

 which the pollen developed or has been stored. 



Sometimes a 3 per cent, to 10 per cent, 

 aqueous solution of cane sugar is entirely sat- 

 isfactory. If there is considerable bursting of 

 the pollen grains soon after sowing, increase 

 the percentage of sugar; decrease the amount 

 if plasmolysis takes place. Solutions should 

 be made up fresh each day. Frequently it has 

 been impossible to secure the optimum germi- 

 nation from simple sugar solutions. Most of 

 the difficulties were avoided and excellent re- 

 sults obtained, when from i per cent, to 2 per 

 cent, gelatin was added to the medium. The 

 gelatine is first made up as a 4 per cent, or 8 

 per cent, solution. Soak the gelatin in cold 

 water, then dissolve with the least possible 

 heating. This solution, without sugar, wiU 

 remain fit for use for several days. From this 

 stock solution of gelatin, dilutions are readily 

 obtained. In making up the germinating 

 medium the diluted gelatin solution is reck- 

 oned as water and the cane sugar added di- 

 rectly to it. While not absolutely exact, per- 

 haps, the method is sufficiently accurate. 

 Thus, for a 4 per cent, solution of sugar in i 

 per cent, gelatin, add one gram cane sugar to 

 24 e.c. of a J per cent, gelatin solution. Com- 

 binations of 3 per cent, to 12 per cent, cane 

 sugar in i per cent, to 2 per cent, gelatin have 

 proved very satisfactory. No definite eombi- 



