288 



SCIENCE 



[N. S. Vol. XLIII. No. 1104 



giving rise to a row of three cells, the innermost 

 of which functions. A normal eight-celled embryo- 

 sac is found. The pollen has been found to germi- 

 nate in nature, and probably fertilization occurs, 

 a process not taking place in those forms where 

 there is no reduction. Division of the fertilized 

 egg is preceded by division of the endosperm nu- 

 cleus. The oldest material available shows an 

 embryo of eight cells, imbedded in conspicuous 

 endosperm cells. The seed shows also the oddly 

 differentiated cells at the chalazal end, as noted 

 by other workers. 



The Prothallm of the Cyatheacece : Alma G. 



Stoket. 



This is a study of fourteen species taken from 

 five of the seven genera of the Cyatheacese .is 

 given by Eugler and Prantl. It includes the sup- 

 posedly primitive form Alsophila quadripinnata 

 C. Chr., also called Lophosoria pruinata Pr. 



In general appearance the prothallia are of the 

 polypodiaceous type, but in the division Cyathe* 

 most of the forms have multicellular hairs on both 

 surfaces of the thallus in the anterior region. 

 These hairs are found only on prothallia which 

 have produced archegonia, never on the male pro- 

 thallia. Lophosoria and the five species of the 

 DicTcsonice which were examined do not have 

 multicellular hairs. The antheridia have a basal 

 cell which is usually wedge-shaped; two ring cells, 

 each of which is connected with the outer wall of 

 the antheridium by a lengthwise wall; and two 

 opercular cells, the smaller of which lifts like a 

 valve. The walls, notably those of the stalk and 

 lid cells, are often cutinized. The archegonia are 

 more like those of Osmunda than those of Pteris 

 and Adiantum. They have one or two basal cells; 

 the walls of the neck cells are thickened and are 

 often cutinized; the necks are usually straight. In 

 young archegonia the neck cells have coarsely 

 granular contents, but the neck cells of older 

 archegonia contain a deeply staining mucilage dif- 

 fering somewhat from that produced by the 

 breaking down of the canal cells. 



Sapid Methods for Qu-antitative and Qualitative 

 Studies on the Soil Flora: Thomas P. Manns. 

 The writer since 1901 has spent much time in 

 the study of soil flora. The greatest difBculties 

 encountered have been methods, apparatus and 

 media that would expedite the work. After much 

 experimental work the writer finds the mechanical 

 shaker (run by electric motor) which accommo- 

 dates sixteen bottles as used for soil analysis, is 

 satisfactory for the preliminary work in properly 



mixing the sample. With the sixteen containers 

 one may work with the surface samples from six- 

 teen different soils at one time, or he may work 

 with eight samples, including a study of the sur- 

 face and subsoils. The time required for the 

 plating of 16 soils in duplicate plates with two di- 

 lutions on four different media (equivalent to 256 

 plates) will be from two and one half to three 

 hours. The dilutions will vary according to the 

 groups from 1/1,000 of a gram, to 1/10,000 and 

 1/100,000 of a gram. The moist sample is pre- 

 pared very fine and one gram is placed in the 

 eight-ounce bottle (nursing) containing 50 c.e. or 

 100 c.c. of sterile water. The sample is shaken 

 fifteen minutes. Other dilutions are made from 

 this source. 



Usually three media will suffice to bring out the 

 important bacterial groups. 



Medium I., for ammonifiers, saprophytic forms 

 including molds, Aetinomycetes, etc. 



Medium II., for B. radioicola. 



Medium III., for Azotoiacter, B. radiohacter 

 and nitrifiers. By means of a constant tempera- 

 ture apparatus, 32 tubes of each of three kinds of 

 media may be kept melted at 43° C. ready for 

 plating. Labelling plates consists in writing soil 

 number, medium number and dilution. For the lat- 

 ter ^ = 1/1,000, .5=1/10,000 and = 1/100,000 

 gram moist soil. 



Media for Quantitative and Qualitative Studies on 

 Asotobacter and Nitrifiers (illustrated by cul- 

 tures) : Thomas P. Manns. 

 Several workers, including Winogradsky, Beije- 

 rinck, Omelianski, Makrinoff and Lohnis have 

 pointed out the difficulties in culturing nitrogen- 

 fixing and nitrifying bacteria. The same workers 

 and others have shown the importance of certain 

 salts, including the carbonates of magnesium and 

 calcium, also the value of phosphates, certain sug- 

 ars, soil extracts or humus. Several have shown in- 

 timate symbiosis between certain nitrogen-fixing 

 forms such as B. radiohacter and Azotoiacter chro- 

 ococcwm. Lohnis in his "Laboratory Methods in 

 Agricultural Bacteriology," p. 97, has shown the 

 stimulating action of magnesium carbonate and 

 calcium carbonate on the nitrifying bacteria. He 

 states in the same work that "Many different 

 methods have already been tried, but the obtaining 

 of pure cultures of the nitrifying organisms is still 

 a most difficult bacteriological problem. The 

 method which is most to be recommended is the 

 gypsum-magnesium-plating method, proposed by 

 Omelianski and Makrinoff." In reference to Aso- 



