604 ME. S. LE M. MOOEE's STUDIES 



munication. He notes that the substance of the closing membrane 

 greatly resembles the slime of sieve-tubes, and thinks that the 

 plates may perhaps result from local differentiation of the parietal 

 protoplasm. Soon after the appearance of Schmitz's paper we 

 find Mr. Hick* returning to the old view of Nageli, but obser- 

 ving that in some cases a " diaphragm," traversed by a strand of 

 protoplasm, is developed within the " collar " through which the 

 connecting-thread passes. Mr. Massee t has recently studied the 

 development of Polysiplwnia urceolata and fastigiata. He figures 

 the cells as, at an early stage of their history, opening into one 

 another by wide canals, unprovided with ring, plate, or membrane, 

 but as afterwards shut off by the formation of plates of cellulose 

 perforated for the passage of threads of protoplasm. Lastly, the 

 subject has been studied by Mr. Gardiner, whose preliminary 

 notice J I have failed in obtaining a sight of, after many endea- 

 vours. However, from a short paper in ' Nature ' (Feb. 26th, 

 1885), it appears that Gardiner's results are, at least in the main, 

 confirmatory of Schmitz's, as he says that, by the aid of chloriodide 

 of zinc, he has been enabled to make out the existence of a pit- 

 closing membrane in every case examined. 



It may then be said that four views of protoplasmic continuity 

 in the Florideae have been enunciated : — 



I. Continuity is direct, by means of a pore functioning as 

 a simple canal of communication. — Nageli (and also 

 Kutzing, Zanardini, &c.). 

 II. Continuity is direct, by means of a wide or narrow 

 strand of protoplasm passing through a ring of harder 

 protoplasmic substance, within the circumference of 

 which a closing membrane may be formed. — Hick. 



III. Continuity direct, but soon interrupted by the formation 



of " stoppers " over the mouths of the pore. — Archer, 

 Wright. 



IV. Except in the Corallines, continuity is indirect always, 



the connecting-threads passing through a pit-closing 

 membrane. — Schmitz, Gardiner. 



Chondeus mamillosus. — The common species of this genus 

 (C. crispus) was very faithfully figured by Kutzing §, the figure 



* ' Journal of Botany,' Feb. and March 1884. 



t Journ. of Eoy. Microsc. Soc. 1884. 



\ Proc. Camb. Phil. Soc. Feb. 11th, 1884. § L. c. tab. 73. 



