ON NAIAS GRAMINEA DEL., VAR. DELILEI MAGNUS. 27 



Chara Braunii are so often associated together as to give a strong 

 colour to the surmise of their common origin. There is nothing in 

 the recorded distribution of Chara Braunii to forbid its being 

 ultimately shown to be aboriginal, but until it is recorded from 

 other British stations, with fewer doubtful surroundings than it 

 has in the Manchester station, it can only be looked upon as a 

 colonist. 



XIX. —A Histological Peculiarity. 



A still stronger proof of its Egyptian extraction is furnished 

 from the histological side. This part of the case has been dealt 

 with by Dr. Magnus, in a paper read to the German Botanical 

 Association at Berlin, December 11th, 1883, and I make no 

 apology for reproducing here the substance of this interesting 

 communication. In describing the structure of Naias graminea on 

 page 13, I mentioned that there were two forms of the plant ; one, 

 possessing peculiar libriform cells near the margin of the leaf ; the 

 other, destitute of these bast-cells. This latter form Dr. Magnus 

 names the var. Delilei, and he states that the English specimens 

 belong to this variety, and indubitabty prove their Egyptian 

 source. The following are some extracts from the paper of 

 Dr. Magnus, published in the ' Berichte der deutseh. Botanischen 

 Gesellschaft,' Jahrg. 1883, Band i., Heft 10 :— 



" I have examined the specimens of Najas graminea collected by 

 Delile in the rice-fields near Bosetta, as also those obtained by 

 Schweinfurth near Benha-el-assl in the Nile Delta, and have found 

 them to be without bast-nerves. They are also wanting in a 

 specimen collected by Gaillardet, near Saida in Syria, which has 

 been kindly communicated . to me by M. Boissier. I was further 

 enabled, through the kind communication of Professor Ascherson, 

 to examine specimens of Najas graminea Del., collected by him 

 during his travels in the Libyan Desert, in the Oasis of Dachl, as 

 also specimens collected by Schweinfurth in the Great Oasis 



J Ohargeh). Prom this it would appear that the Najas graminea 

 )el., collected in a brook at A'in-Scherif hear Kasr Dachl, as well 

 as those collected by Ascherson near El Ohargeh, likewise have 

 leaves without libriform cells, like the plants of Lower Egypt. On 

 the other hand, the N. graminea collected some weeks later in the 

 same ditches in A'in-Scherif by Ascherson, as well as from a warm 

 spring-hole in Kasr Dachl, as also the specimens collected by 

 Schweinfurth near Ohargeh, have all well- developed bast-nerves, 

 similar to the plants of Oordofan, Djur, Algeria, Celebes, &c. . . . 

 " The absence of these bast-nerves in a variety of Najas 

 graminea is the more peculiar, as through the construction of the 

 male flower of N. tenuifolia B. Br. [see fig. 15, Plate 251] , from 

 Australia, which differs so materially, has precisely the same bast- 

 nerves in exactly the same shaped libriform cells on the leaves ; 

 consequently these bast-nerves represent the distinctive character 



of a group of allied species, but still subject to variations 



" I have mentioned above that the one set of specimens from 

 Kasr-Dachl and Ohargeh had leaves without bast-nerves, and 



