ICE IN PLANT TISSUE. 2/ 



Since i860 the studies of Goeppert.* Prillieux.f AIuller-Tluir- 

 gan.]; Kunisch.§ and ■\rolisch|| have all shown that, in nature, ice 

 very rarely forms within the cell, and that cells are rarelv, if ever, 

 ruptured by ice formation. The cases where the sap freezes 

 within the cell have been found limited to large cells that are verv 

 rich in water, containing little protoplasm, and having large 

 vacuoles, as for example, the large internodal cells of Chora and 

 A'itclla, the epidermal cells of Tradcscaiitia (Molisch), and a few 

 similar cases. Even in Chara and Xifella the ice is produced 

 within the cell only when the freezing is rather rapid. Cells that 

 are cutinized nearly all the way around, and which consequently 

 have no external water film in which ice may start, also produce 

 ice within. The cells of varicnis plant hairs are of this nature. 

 ?\Iolisch has studied in detail the freezing of Spirogxni threads, 

 finding that the water passes to the surface in almost every case, 

 while the cell itself collapses completely. Kunisch found the same 

 true for Xitel la. Colin* claims to have found ice between the 

 wall and protoplasm in Xitella syiicarpa. and Goeppert the same 

 in Cladophora fracta, but no one else has verified these observa- 

 tions. On the other hand, Mtiller-Thurgau has shown that ice 

 forms exclusively in the intercellular spaces only when the tissue 

 is very gradually brought to the point of ice formation. Fresh 



* Goeppert. Ueber Einwirkung niederer Temperatur auf die Vegetation. 

 Gart. Flora Deutsch. Russ. u. d. Schweiz. 1879. 



Ueber das Gefrieren, Erfrieren der Pflanzen und Schutzmittle dagegen. 

 Stuttgart (book), 1883. 



t Prillieux. Snr la formation de glacons a I'interieur des plantes. Ann. 

 Sci. Nat. ser. 5, 12 : 125. 1869. 



t Midler-Tliurgau. Ueber das Gefrieren und Erfrieren der Pflanzen. 

 Landw. Jahrb., g: 133. 1880 and 15: 453. 1886. 



§ Kuniscb. Ueber die todlicbe Einwirkung niederer Temperaturen auf 

 die Pflanzen (book). 1880. 



II Moliscb. Untersuchungen iiber das Erfrieren der Pflanzen (book). 

 1897. 



Oberdieck. Beobacbtungen lilier das Gefrieren der Gewiicbse. etc. 

 (book). Ravensburg. 1872. 



Dalmar. Ueber Eisbildung in Pflanzen mit Riicksicbt auf die anatoni- 

 iscbe Beschaffenheit derselben. I-'lora, 80: 436. 1895. 



* Cohn. Report of a paper read before Die Schlesiscben Gesellschaft f. 

 vaterland. Cultur. P'ot. Zeit. 29: /2^. 1871. 



