TRANSACTIONS OF THE SECTIONS. 9 
was that the septa were not straight lines, and not inclined to each other at angles 
of 120°; but in the posterior surface of the other there were sia septa, placed so 
unsymmetrically, as in fig. 4, that five of them 
were in one semicircle, while only one was in the 
other, 
When the lenses now described were immersed 
in distilled water and examined by polarized light, 
the optical figures which they exhibited were not 
in the slightest degree disturbed by the want of 
symmetry in the number and position of their 
septa. 
It will be seen from the figures, that in number- 
ing the septa I have counted only those from 
which the groups of fibres, or vortices as they have 
been called by Leeuwenhoek, take their origin. 
If the abnormal structures now described are 
the result of disease, or of that change in the 
lens which is produced by age, it is very probable that several of the varieties of 
structure observed in the human crystalline are abnormal. Reil* thought he saw 
in a human foetus, seven months old, st septa radiating from each pole, while 
in adults there were only four. Dr. Thomas Young has given a drawing of 
the human crystalline (fig. 93) in which the fibres occupy ten groups or vortices, 
separated by ¢en radial lines extending from the margin to the centre of the lens, 
each fibre being parallel to their radii, and consequently meeting at an acute angle. 
In another figure, 95, he represents what he calls ramifications from the margin of 
the crystalline lens, that is, ramifications of fibres, a structure which is wholly in- 
compatible with his fig. 93, showing the order of the fibres of the human crystalline. 
No other observer has seen such an arrangement of fibres either in the human cry- 
stalline or in any other lens. It is obvious, indeed, that Dr. Young did not possess a 
correct method of tracing the fibres to their origin, because he makes their arrange- 
ment in Fishes similar to their arrangement in Birds, that is, extending from pole to 
pole like the meridians of a globe}, a structure contrary to the results obtained by 
every observer. ; 
In his ‘ Icones Oculi Humani,’ Soemmering § has given two very minute drawings 
of the crystalline ; and has inferred merely from its mode of splitting after macera- 
tion in alcohol, that it divides into four unequal segments, and that in each of these 
four there are four fissures ; and though he afterwards found that by “a careful and 
continued maceration ” in alcohol it separated into fibres, yet he argues that this is 
no proof that the recent or the living Jens has a fibrous structure “like the zeolites! ” 
Had he been acquainted with the existence of teeth in each fibre by which they are 
held together to give solidity and permanence of form to a soft and semifluid body, 
he could not have considered, as he does, the crystalline lens to be merely a lenti- 
cular humour “like a drop of dissolved gum ||.” 
In consequence of these contradictory opinions respecting the structure of the 
human crystalline, I was anxious to study it by means of the optical method which 
had occurred to me of tracing the fibres to their origin by the diffracted images which 
they produced. 
In some lenses, the age of which I did not know, I found three septa, as in 
quadrupeds. 
In two very large lenses there were on each side four septa, two being placed at 
each end of a central line, like that which forms the two septa in the Hare and Sal- 
mon. This structure is shown in the Phil. Trans. 1836, plate 6. figs. 3, 4, but in 
the human lens the central line was very much shorter than in these figures. The 
* Lentis crystalline structura fibrosa. Preside Reil. Defendit Samuel Godofredus Sattig, 
Silesius. Hale, 1795, p. 14, 29. 
_+ Phil. Trans. 1800 ; or Elements of Nat. Phil. vol. ii. p- 605. plate 12. fig. 93. 
t Phil. Trans. p. 605. fig. 100. 
§ Francofurti ad Meenum, 1804, p. 67, tab. 5. figs. 17, 18. 
| Instar gummi liquefacti. Icones, &c. p. 68. 
