SEEDAGE 



jected; also if 1 per cent or more of weed seeds be 

 found. 



The reference collection of seeds should be kept in 

 neatly labeled glass bottles, without necks, tightly 

 stoppered and systematically arranged in shallow paste- 

 board boxes (see Fig. 2295). A convenient size for these 

 bottles is 2 in. long by 3-5 in. in diameter. A tray 

 holding 100 of such bottles should fit into an ordinary 

 herbarium case. If the collection is large, a card index 

 will be of great assistance in finding the specimens. 



i:, in, illation Tints. — The seeds used in germination 

 tr~i' inii-1 i>c t;iki-u indiscriminately from pure seed 

 wlii.li lia^ Ih , 11 thoroughly mixed for that purpose. 

 Thr srlfci.iiiu of plump, uice-lookiug seeds for these 

 tests, ;is Ireipiuutly practiced, impairs the authenticity 

 of the result. 



Tests may be conducted in the laboratory between 

 damp cloths or blotters, or in porous saucers, or in sand 

 or snil in :i irrcenliouse. Seeds which are known to ger- 

 Hiiiiiii. «uli <li(iii-ulty should be tested in a greenhouse 

 ;i~ ' II I M laboratory. The same is true of any 

 ^|i. I ■ .ln.se conditions of germination are not 



SEEDAGE 



1643 



may be used for the insertion of a thermometer, if de- 

 sired. Owing, however, to the iufiueuce which the ex- 

 ternal atmosphere exerts upon thermometers whose 

 tubes are partly exposed, provision has been made for 

 holding two thermometers in a horizontal position, one 

 on the inside of each panel of the door to the chamber, 

 by means of hooks of stout copper wire (Fig. 2297, a, a). 

 The iloor is made in 2 panels each consisting of 2 

 \i\M t tl ck glass set about 2 m apart in a copper 

 fran 11 i I 1 1 f It The inside 



I lojection (Pig. 

 1 groove (Fig. 



answer as wrll f,.r liiu-, sl..\v-i,'.TMiinat 111- smN like 

 tobacco ami June grass, and many llower-.si-c.ls, owing 

 to the fact that the blotters sometimes adhere too closely 

 to permit the proper circulation of air. This may be 

 remedied to a certain extent by placing narrow strips of 

 glass between the folds, but main reliance in such cases 

 should be placed upon soil tests. 



All tests are to be made in duplicate, using two lots 

 of 100 seeds each of peas, beans, corn, cucurbits and 

 others of a similar size, and 200 seeds of clover, cab- 

 bage, lettuce, etc. The more seeds taken for test the 

 less the chance of error. However, 5 per cent to 10 per 

 cent of variation may be expected between the two lots 

 of seed, even though they might have been taken from 

 the same plant. In the case of a greater variation than 

 10 per cent the test should be repeated. Seeds upon 

 which moulds form quickly are likely to be old stock. 



The seeds should be inspected daily, a note being 

 made of those having sprouted, which are then thrown 

 out In testing seeds of the pea f iiii 

 ily (Leg in no a?) onethiri cf those 

 leraaiuing hard and fresh at the clo e 

 t th te t aie u lallj counted as hav 

 I I Ihe average of the 



1 } 1 t be taken as the 



1 f lity A-\ erages 



ill 1 1 however between 



1 I I different methods 



I le preferal I5 male 



net 1 U ul 1 h ited 1 y 5, i the heat 

 bemgcontrolle 1 1 y athermc legulit 1 

 The blotters must be free fi m soluble 

 chemicals Blue blotters will 1 e foun 1 

 less trying to the eye than white. The 

 germinating chamber may be of any 

 form which allows proper control of 

 the conditions of light, heat, air and 

 moisture. The standard chamber 

 adopted by the association of Ameri- 

 can Agricultural Colleges and Experi- 

 ment Stations was designed by the 

 writer, and serves equally well for 

 bacteriological purposes or experi- 

 ments in plant phvsiology as for seed 

 testing (see Fig. 2296). " 

 It is made of 20-ounce corrugated copper, and is 2 feet 

 long, 18 inches deep, and 2 feet high, outside measure- 

 ments. The outside, except the bottom, is covered with 

 two layers of felt, each J^ inch thick. 



A water space is afforded by the double walls, which 

 extend on all sides except the front and are 2 in. apart. 

 Entrance to this water jacket is obtained at a, d (Fig. 

 22961, while the water can be drawn off at jr. At c, 0, on 

 the top. and at t, near the bottom of one end, are 1-inch 

 openings into the chamber. One of the upper openings 



Bottle similar to 

 that used in 

 U. S. Dept. 

 Aeric. for small 



mits the exit of carbon dioxid, and can be closed tightly 

 with a slide. Perfect closing of the door is further ef- 

 fected by a copper slide extending along the front mar- 

 gin, which catclies firmly at the top and bottom of the 

 chamber (Fig. 2297, d, d). This device, together with 

 the groove and its corresponding projection, are adapted 

 from the Rohrbeck bacteriological chamber. The out- 

 side door is furnished with a frame into whichj slide 

 two plates of galvanized iron painted dead black inside 

 and covered with felt (Fig. 229fi, ), ,7). By this arrange- 

 ment the intrrir.r .if th.- .■lii.iiih.'r urn- l... k.-pt dark or 



exposed to Ul!-' •'' -'■■'' ''ii.- liilf '•■■•y be dark 



and the resi k ' , -.in. miing the 



same. By nu- • '. ■ -i' 1 ■ .is can be 



read without .-i" himu 1 1..- ■!.".,■. . ; In ^ , plui. . ..f various 

 colors may be substituted for the sli.les. if the effects 

 of different rays of light on plant-growth are to be 

 studied. 



Seven movable shelves, placed 2'^ in. apart, are held 

 in place by copper ledges K inch wide. These shelves 

 are made of brass rods IH in. apart, and each one is 

 capable of holding up 60 pounds weight. The tempera- 

 ture is controlled by a low-temperature thermo-regulator 

 (Pig. 2296, 6). A very low and equable llame is secured 

 with a microbunsen "burner (Pig. 2296. e). One of the 

 openings into the water jacket (Pig. 2296, a) is 2 in. in 

 diameter to admit a Koux thermo-regulator, if a very 



