174 KRAEMER — CONTINUITY OF PROTOPLASM. [April 4. 



having been gradually accomplished after birth, gross bulbar dis- 

 turbance, blindness, faulty muscle action, and coarse atrophic dis- 

 order have not been produced, and hence remain unmentioned as 

 ordinary consequences in such cases. 



Blindness from deprivation (postnatal causes), as in the wide- 

 world known case of Laura Bridgman, which on autopsy was found 

 to be associated with optic nerve and optic tract atrophy and thin- 

 ning of the gray matter of the occipital cortex, is also a subject for 

 discussion elsewhere. 



ON THE CONTINUITY OF PROTOPLASM. 



BY HENRY KRAEMER, PH.D. 

 (Plates XXI and XXH.) 

 {Read April I^, 190S.) 



While Schleiden^ conceived each cell to have an independent 

 existence, Hofmeister' contended that the protoplasts of contigu- 

 ous cells are united,, forming a higher unity; that is, one synplast. 

 In later years both Sachs * and Strasburger ^ have supported the view 

 of Hofmeister. And even so great an authority as Nageli ® ex- 

 pressed the view that neighboring plant cells are united by means 

 of threads of protoplasm in much the same manner as in the sieve 

 tubes first described by Hartig ® some thirty years before. 



In 1878 Thuret and Bornet' first called attention to the fact that 

 in certain of the Florideae the contents of certain of the cells of 

 the trichophore and carpogonium are directly connected by means 

 of pores. Fromann * appears first to have called attention to the 

 direct connection of protoplasm in the higher plants, in the epider- 

 mal and parenchyma cells in the leaves of Rhododendron and Dra- 

 cena. While TangP was preceded by these several investigators, 

 the establishment of the view that there is a continuity of proto- 

 plasm is due for the most part to his researches. On treating dry 

 sections of the endosperm of Strychnos Nux vomica with dilute 

 iodine solutions, he observed a distinct lamellation of the cell wall 

 as well as the formation of yellowish striae, which latter he con- 

 ceived to be plasma threads connecting the different cells. The 

 appearance thus produced he compares to the structure of the sieve 

 tubes, but in speaking of the contents of the latter, he states that 



