STOMATA. 



71 



tions hereafter to be described, the stoma being in fact a deh- 

 catel}- balanced valve. A vertical section shows that the outer 

 part of the opening is wider than the narrow passage farther 

 down, and that the space below this widens somewhat towards 

 the intercellular cavity.^ 



1 The following table, compiled from figures given by Weiss, gives the num- 

 ber of storaata on the upper and under sides of the leaves of various plants 

 for the most part readily pi-ocurable by students. To sliow the wide differences 

 in size, the longer and shorter diameters have been added, and, finally, the frac- 

 tion of a square millimeter covered by a single stoma. 



Name of plant. 



Abies balsamea 



Abies nigra 



Acer Pseudoplatanus, L. . . 



Amarantus cauilatus, L. , . 



Anemone iiemorosa, L. . . . 

 Asclepias incaruata, L. , . . 



Aveiia sativa, L 



Berberis vulgaris, L 



Betula alba, L • 



Brassiua cileracea, L 



Buxus serapervirens .... 



Caltlia palustris, Ij 



Euphorbia Cyparissias, L. . 



Ficus elasticti 



Galantlius nivalis, L . . . . 

 Geranium Robertianum . . . 

 Heliantbus annuus, L. . . , 

 Hydrangea quercifolia, Bertr. 



Ilex Cassine 



Juglans nifira, L, . . . 

 Lilium bulbiferum, L. ... 

 Madura aurantiaoa, Nutt. , . 

 Mim.osa pudica, L 



Morus alba, L 



NyrapliiBa alba, L 



Piiius Strobus, L 



Piuus sylvestris, L. .... 



PisuiQ sativum, L 



Pittosporam Tobira, Alt. . . 



Populus dilatata, Ait. . . . 



Ribea aureura, Pursli .... 



Secale cereale, L 



Sequoia gigantea (young plants) 



Sileiie inflata, Sm. 



Solanum Dulcamara .... 



Stellaria media, Sm 



Syriuga vulgaris, L 



Vinca minor, L 



Vinca minor, var. variegata . 

 Zea Mais, L 



Number in 

 sq. mm. 









31 







171 





 67 











219 















30 



176 

 

 

 

 

 



460 



142 



BO 



101 







55 









 71 

 60 

 128 

 

 

 

 91 





228 



82 



400 



67 

 191 



27 



229 

 237 

 301 

 208 



43 

 259 

 145 



55 

 297 

 325 

 330 

 213 

 461 



62 

 251 











71 



2r6 



145 



25 



82 



166 



263 



477 

 4(15 

 158 



0.047 



0.042 



0.024 



I 0.012 



j 0.020 



045 



0.026 



1 0.051 



i O.OGO 



0.033 



0.029 



032 

 042 

 0.027 

 0.028 

 0.034 

 045 

 0.034 

 0.020 

 0.029 

 0.024 

 0.071 

 0.022 

 (0.017 

 I 0.026 

 I 0.018 

 I 0.029 

 0.026 

 0.051 

 0.034 

 0.024 

 031 

 ; 035 

 0.0:J3 

 0.036 

 0.051 

 0.053 

 0.033 

 0.021 

 029 

 O.OiS 

 0.029 

 0.024 

 0.037 



0.031 



0.027 



017 



I 0.012 



j 0.017 



040 



018 



I 035 



i 0.050 



0.022 



0.018 



0.031 

 0,03* 

 0.018 

 019 

 0.022 

 0.032 

 0.023 

 0.019 

 0.025 

 018 

 0,050 

 0.016 

 I 0.009 

 I 0.015 

 I 0,008 

 1 0.021 

 0.022 

 0.032 

 0.023 

 0.017 

 0.027 

 ( 0.024 

 1 0.021 

 025 

 029 

 0.033 

 0.021 

 0.014 

 0.036 

 018 

 0.018 

 0.016 

 0.029 



The space in a 



sq. mm covered 



by a stoma. 







0.0270 









 0247 



0.0706 









 0.1137 

















 0.0176 



0.1074 

 

 

 

 

 



0.0104 







2070 

 0.1945 

 O.O307 

 0.0323 

 



0.0303 





 





 0.0386 

 0.0139 

 0.0758 













 0.0792 



0.2B60 

 11.0731 

 0.1280 



0.0947 

 0703 



0.0554 



0,1305 

 0,0972 



0.0942 

 0.0482 

 0.0989 

 0.1187 

 0.0323 

 0.3356 

 0.1995 

 0.1015 

 0.1206 

 0.1503 

 0.1751 

 0.0695 



0.0927 

 0.0547 



0.04.36 

 0.0091 

 0.2494 



0.1471 



0.1025 

 0269 

 0.1434 

 0905 

 0.0607 



0.1162 

 0.1961 

 0.1223 

 0,1332 



