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Consequently one single type exists only; this is represented in 
fig. 1(D. We may also represent this diagram by B, + B, + B, 
This means that the P,7-diagram consists of three onecurvical bundles. 
2. Binary systems. (Two components, four curves). Four curves 
may be divided over three bundles in one single way only, viz. 
in such a way that one bundle contains two curves and two bundles 
each one curve. We represent this by B, + B, + B, [the symbol 
B, represents a bundle which contains 7 curves]; this means that 
the P,T-diagram consists of two onecurvical and one twocurvical 
bundle. Fig. 2(I) gives a representation of this diagram. 
3. Ternary systems. (Three components, five curves). 
When dividing five curves into an odd number of bundles we may 
distinguish two principal types, viz. a division over 5 and over 3 
bundles. With a division over 5 bundles, the diagram: 
B, + B, + B, + B, + B, 
arises, consequently a P,7-diagram with five onecurvical bundles, 
as is also represented in fig. 2 (ID). 
With a division over 3 bundles 2 diagrams may arise, viz.: 
B, + B, JB, and B, + B, + B, 
The first diagram consists of two onecurvical and one threecur- 
vical bundle and is represented in fig. 6 (ID), the second consists of 
one onecurvical and two twocurvical bundles and is drawn in fig. 4 (II). 
4. Quaternary systems. (Four components, six curves). 
When dividing the 6 eurves into bundles we may also distinguish 
two principal types, viz. a division over 5 and over 3 bundles. 
With a division over 5 bundles the diagram 
Bt B 1B, B, = B: 
arises, consequently a P,7-diagram with one twocurvical and four 
onecurvical bundles. We find this drawn in fig. 4 (IID. 
With a division over 3 bundles the diagrams: 
B,+ B,+ B, Bt B, + B, and B, + B, + B, 
may arise. 
The first consists of one fourcurvical and two onecurvical bundles, 
we find this in fig. 8 (III); the second consists of one onecurvical, 
one twocurvical and one threecurvical bundle and is drawn in 
fig. 6 (III). The third consists of three twocurvical bundles and is 
found in fig. 2 (If). 
5. Quinary systems. (Five components, seven curves). 
With a division of 7 curves into an odd number of bundles we 
