184 



SCIENCE 



[N. S. Vol. XLI. No. 1048 



of related species of oak. Otlier characters whicli 

 agree closely with general conditions in traumatic 

 tissue are as follows: A vertical shortening of the 

 broad rays. The presence of knarls which appear 

 only in tangential sections of the gall. A parting 

 of the fibers to right and left in the vicinity of 

 the larval chambers. Areas of isodiametric 

 parenchyma cells with lignified walls, and a 

 shortening of many of the other cells of the wood. 

 A reduction in the number or an entire lack of 

 vessels. Absence of distinct annual rings of 

 growth. A suggestion of a return of the cam- 

 bium to its normal activities in the outermost lay- 

 ers of wood. Woody inclusions in the bark. 

 The Anatomy of a Peridermium Gall: Alban 



Stewart. 



Large woody galls occur on the branches of the 

 jack pine, Finns Banksiana Lamb., which are 

 caused by an infection of Per{dermium (Aeeidium) 

 cereirum Pk. The following anatomical differ- 

 ences occur in the woody portions of these galls 

 as compared with the normal wood of this spe- 

 cies of pine. A greatly increased production of 

 woody tissue. An increase in the number, and a 

 broadening of the rays both vertically and tan- 

 gent ially, characters which also appear in trau- 

 matic wood of this species. The presence of 

 knarls in tangential sections. A greatly increased 

 production of resin canals in the gall, but no such 

 increase in the normal wood close by. A shorten- 

 ing of many of the tracheids as well as blunt end 

 walls and wavy side walls of the same. Cells 

 which partake of the character of both tracheids 

 and parenchyma cells in their pitting. Alternate 

 as well as opposite arrangement of pits in the 

 walls of the tracheids. Apparently an absence of 

 bars of Sanio from the walls of the tracheids in 

 many instances. 



A Note on the Leaf Anatomy of Avicennia: Al- 

 ban Stewart. 

 On the Forms of Castela galapageia HooTc. f.: 



Alban Stewaet. 

 Photographing Mosses: A. J. Gkout. 



When beginning the study of mosses I found 

 identifications very difficult because of the lack of 

 suitable and adequate literature and illustrations. 

 I did not have access to Sullivant 's "leones" or 

 the ' ' Bryologia Europasa. ' ' 



When as an advanced student I had access to 

 these works I formed the ambition to put similar 

 but cheap and simplified books within the reach 

 of any enterprising student. My desire was to 

 make new moss students instead of new moss 



species, because what we need to advance bryology 

 in America is, first of all, more observers and col- 

 lectors. 



The two books I have published were illustrated 

 by drawings, many of which were taken from the 

 standard works mentioned above. But I saw how 

 valuable "photogi-aphs were in the study of flow- 

 ers, ferns, etc., and I became ambitious to equal 

 this work in the mosses and hepaties. To this end 

 I have devoted my spare time for the past year or 

 two, and I have succeeded in enlisting others. 

 Professor Holzinger has done some excellent work. 



My outfit is a Bausch and Lomb camera for 

 micro-photography with a heavy iron base and 

 long bellows. Instead of the cap to fit over the 

 eye-pieee of the compound microscope I put in a 

 lens-board or boards. I have a battery of three 

 lenses, a Wollensaek Anastigmatic F. 6.8 for a 

 4 by 5 camera and a supplementery lens to 

 shorten the focus. A Beck Neostigmar 3 in focus, 

 f. 3.5, wide angle from a motion-picture camera 

 and a Bausch and Lomb wide angle Zeiss-protar, 

 focal length 2J inches. 



The Wollensaek and supplement give magnifi- 

 cations up to 5 diameters, and the automatic shut- 

 ter makes it more convenient than the others, which 

 have to be uncapped. Also it gives plenty of il- 

 lumination for focusing. The Beck gives magni- 

 fications up to 7 diameters and also admits plenty 

 of light for focusing. The Zeiss protar is so small 

 that focusing is difficult unless bright sunlight 

 shines on the object, but I can get 9 diameters. To 

 get depth the lenses were stopped down to 32, 

 64 or even to 128 V. S., and in strong light were 

 given from 3 min. at 32 U. S. to 6-8 man. at 

 U. S. 64 when cloudy bright and indoors. 



If the mosses were not dry the setae would 

 sometimes twist during the longer exposures so 

 as to produce a bad blur. I have had better re- 

 sults with reflected light than transmitted light. 

 I am undecided as to whether a black background 

 is superior to a white or not. Against the black 

 background every speck of dust magnified ten- 

 fold produces a disagreeable effect. 



I have also tried peristomes by transmitted 

 light under a compound microscope. I squandered 

 more than a dozen plates on the peristome of 

 Ceratodon, but its dark red color and density 

 foiled my attempts to get anything but a sil- 

 houette. 



The photographs themselves will tell you far 

 more than I can as to my results. 



Geokge T. Moore, 



Secretary 



